Coating compositions for application utilizing a high transfer efficiency applicator and methods and systems thereof

ABSTRACT

A method of applying a coating composition to a substrate utilizing a high transfer efficiency applicator include the steps of providing the high transfer efficiency applicator comprising an array of nozzles wherein each nozzle defines a nozzle orifice having a diameter of from 0.00002 m to 0.0004, providing the coating composition, and applying the coating composition to the substrate through the nozzle orifice without atomization such that at least 99.9% of the applied coating composition contacts the substrate to form a coating layer having a wet thickness of at least 5 microns, wherein the coating composition includes a carrier, a binder, and a radar reflective pigment or a LiDAR reflective pigment. The coating composition has an Ohnesorge number (Oh) of from about 0.01 to about 12.6, a Reynolds number (Re) of from about 0.02 to about 6,200, and a Deborah number (De) of from greater than 0 to about 1730.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/768,309, filed on May 29, 2020, which is a US National-Stage entryunder entry under 35 U.S.C. § 371 based on International Application No.PCT/US2018/063457, filed Nov. 30, 2018, which was published under PCTArticle 21(2) and which claims priority to U.S. Provisional ApplicationNo. 62/593,022, filed Nov. 30, 2017, U.S. Provisional Application No.62/593,026, filed Nov. 30, 2017, and U.S. Provisional Application No.62/752,340, filed Oct. 30, 2018, which are all hereby incorporated intheir entirety by reference.

TECHNICAL FIELD

The technical field generally relates to coating compositions forapplication to a substrate, and more particularly, to coatingcompositions for application to substrates utilizing high transferefficiency applicators.

BACKGROUND

Ink jet printing is a non-impact printing process in which droplets ofink are deposited on a substrate, typically paper or textile fabrics, inresponse to an electronic signal. This application process has theadvantage of allowing digital printing of the substrate which can betailored to individual requirements.

The drops can be jetted onto the substrate by a variety of inkjetapplication methods including continuous and drop-on-demand printing. Indrop-on-demand printing the energy to eject a drop of ink can be from athermal resistor, a piezoelectric crystal, acoustic or a solenoid valve.

In the automotive industry, the vehicle body is typically covered with aseries of finishes including an electrocoat, a primer, a coloredbasecoat providing the color and a clear topcoat to provide additionprotection and a glossy finish.

Currently most automobile bodies are painted in a single color with thebasecoat being applied in a single spray operation. The coating isapplied with pneumatic spray or rotary equipment producing a broad jetof paint droplets with a wide droplet size distribution. This has theadvantage of producing a uniform high-quality coating in a relativelyshort time by an automated process.

However, this process has a number of disadvantages. If the vehicle bodyis to be painted with multiple colors, for example a second color isused for a pattern such as a stripe, or a whole section of the vehiclebody such as the roof is painted a different color, this requiresmasking the first coating and then passing the vehicle body through thepaint spray process a second time to add the second color. After thissecond paint operation the masking must be removed. This is bothtime-consuming and labor-intensive adding significant cost to theoperation.

A second disadvantage of the current spraying technology is that thedrops of paint are sprayed in a wide jet of droplets which has a widerange of droplet sizes. As a result many of the droplets do not land onthe vehicle, either because they are sprayed near the edges and sooverspray the substrate, or because the smaller droplets have too low amomentum to reach the vehicle body. This excess overspray must beremoved from the spray operation and disposed of safely leading tosignificant waste and also additional cost.

Accordingly, it is desirable to provide coating compositions suitablefor application to a substrate utilizing a high transfer efficiencyapplicator. Furthermore, other desirable features and characteristicswill become apparent from the subsequent detailed description and theappended claims, taken in conjunction with this background.

BRIEF SUMMARY

This disclosure provides a method of applying a coating composition to asubstrate utilizing a high transfer efficiency applicator, the methodcomprising the steps of:

providing the high transfer efficiency applicator comprising an array ofnozzles wherein each nozzle defines a nozzle orifice having a diameterof from 0.00002 m to 0.0004 m;

providing the coating composition; and

applying the coating composition to the substrate through the nozzleorifice without atomization such that at least 99.9% of the appliedcoating composition contacts the substrate to form a coating layerhaving a wet thickness of at least 5 microns;

wherein the coating composition comprises:

-   -   a carrier;    -   a binder present in an amount of from 5 to about 70 weight        percent based on a total weight of the coating composition;    -   a crosslinker present in an amount of from about 0.1 to about 25        weight percent based on a total weight of the coating        composition; and    -   a radar reflective pigment or a LiDAR reflective pigment; and

wherein the coating composition has

-   -   (1) a solids content of from about 5 to about 70 weight % based        on a total weight of the coating composition as measured in        accordance with ASTM D2369;    -   (2) a viscosity of from about 0.002 Pa*s to about 0.2 Pa*s as        measured according to ASTM 7867-13 with cone-and-plate or        parallel plates at a shear rate of 1000 sec−1;    -   (3) a density of from about 838 kg/m³ to about 1557 kg/m³;    -   (4) a surface tension of from about 0.015 N/m to about 0.05 N/m;    -   (5) a relaxation time of from about 0.00001 to about 1 s;    -   (6) an Ohnesorge number (Oh) of from about 0.01 to about 12.6        that is determined in accordance with equation I, as follows:

Oh=(η/√{square root over (ρσD)})  (I),

-   -   wherein η represents viscosity of the coating composition in        pascal-seconds (Pa*s), ρ represents density of the coating        composition in kilograms per cubic meter (kg/m³), σ represents        surface tension of the coating composition in newtons per meter        (N/m), and D represents nozzle diameter of the high transfer        efficiency applicator in meters (m);    -   (7) a Reynolds number (Re) of from about 0.02 to about 6,200        that is determined in accordance with equation II, as follows:

Re=(ρvD/η)  (II),

-   -   wherein ρ represents density of the coating composition in        kilograms per cubic meter (kg/m³), v represents impact velocity        of the high transfer efficiency applicator in meters per second        (m/s), D represents nozzle diameter of the high transfer        efficiency applicator in meters (m), and it represents viscosity        of the coating composition in pascal-seconds (Pa*s); and    -   (8) a Deborah number (De) of from greater than 0 to about 1730        that is determined in accordance with equation III, as follows:

De=λ/√{square root over (ρD ³/σ)}  (III),

wherein λ represents relaxation time of the coating composition inseconds (s), ρ represents density of the coating composition inkilograms per cubic meter (kg/m³), D represents nozzle diameter of thehigh transfer efficiency applicator in meters (m), and a representssurface tension of the coating composition in newtons per meter (N/m);and

wherein the impact velocity is from about 0.2 m/s to about 20 m/s.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the disclosed subject matter will be readilyappreciated, as the same becomes better understood by reference to thefollowing detailed description when considered in connection with theaccompanying drawings wherein:

FIG. 1 is a perspective view illustrating a non-limiting embodiment of asystem for applying the coating composition to the substrate utilizingthe high transfer efficiency applicator;

FIG. 2 is a chart illustrating a non-limiting embodiment of a generalrelationship between the Ohnesorge number (Oh) and the Deborah number(De) for the coating composition;

FIG. 3 is a chart illustrating a non-limiting embodiment of a generalrelationship between the Reynolds Number (Re) and the Ohnesorge number(Oh) for the coating composition;

FIGS. 4A and 4B are chart illustrating a non-limiting embodiment of ageneral relationship between the Reynolds Number (Re) and the Ohnesorgenumber (Oh) for the coating composition;

FIGS. 5A and 5B are chart illustrating a non-limiting embodiment of ageneral relationship between the Reynolds Number (Re) and the Ohnesorgenumber (Oh) for the coating composition;

FIG. 6 is a chart illustrating a non-limiting embodiment of a generalrelationship between impact velocity and satellite droplet formationrelative to nozzle diameter.

FIGS. 7A and 7B are images illustrating a non-limiting embodiment ofanother general effect of extensional relaxation and shear viscosity ofthe coating composition;

FIGS. 8A and 8B are images illustrating a non-limiting embodiment ofanother general effect of extensional relaxation and shear viscosity ofthe coating composition;

FIGS. 9A and 9B are images illustrating a non-limiting embodiment ofanother general effect of extensional relaxation and shear viscosity ofthe coating composition;

FIGS. 10A, 10B, 10C, and 10D are cross-sectional perspective viewsillustrating a non-limiting embodiment of a high transfer efficiencyapplicator;

FIG. 11 is a perspective view illustrating a non-limiting embodiment ofa high transfer efficiency applicator including a plurality of nozzles;

FIG. 12 is a perspective view illustrating another non-limitingembodiment of a high transfer efficiency applicator including aplurality of nozzles;

FIG. 13 is a perspective view illustrating a non-limiting embodiment ofa high transfer efficiency applicator assembly including a four hightransfer efficiency applicators;

FIG. 14 is a cross-sectional perspective view illustrating anon-limiting embodiment of a multilayer coating including a coatinglayer formed from a coating composition;

FIG. 15 is a perspective view illustrating a non-limiting embodiment ofa substrate including a first target area 80 and a second target area82;

FIG. 16 is a perspective view illustrating a non-limiting embodiment ofa substrate including a coating layer having a camouflage pattern;

FIG. 17 is a perspective view illustrating a non-limiting embodiment ofa substrate including a coating layer having a two-tone pattern;

FIG. 18 is a perspective view illustrating a non-limiting embodiment ofa substrate including a coating layer having a striping pattern;

FIG. 19 is a perspective view illustrating a non-limiting embodiment ofa substrate including a coating layer having an irregular pattern; and

FIG. 20 is a graphical representation of properties of various coatingcompositions.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit coating compositions as described herein.Furthermore, there is no intention to be bound by any theory presentedin the preceding background or the following detailed description.

Applying coatings using a printhead, similar to an inkjet printhead, mayprovide a solution for applying two colors to a vehicle and forminimizing overspray by generating drops of a uniform size that can bedirected to a specific point on the substrate, in this case a specificlocation the vehicle body, thus minimizing, or completely eliminatingoversprayed droplets. In addition, digital printing can be used to printpatterns or two tones on the vehicle body, either as a second colordigitally printed on the top of a previously sprayed basecoat of adifferent color, or directly onto the primed or clearcoated vehiclesubstrate.

However, conventional inkjet inks have typically been formulated toprint on porous substrates such as paper and textiles where the ink israpidly absorbed into the substrate thus facilitating drying andhandling of the substrate shortly after printing. In addition, althoughthe printed articles have sufficient durability for these applications,such as printed text and pictures, or patterned fabrics, the durabilityrequirements of an automotive coating are far greater in terms of bothphysical durability, such as resistance to abrasion and chipping, andlong-term durability to weathering and light resistance. Furthermore,ink jet inks known in the art are formulated to have a low and generallyshear-rate independent, or Newtonian, viscosity, typically below 20 cps.This is because of the limited amount of energy available in each nozzleof a printhead to eject a drop and also to avoid thickening of the inkin the channels of the printhead potentially leading to clogging.

In some embodiments, by contrast an automotive coating typically has asignificant non-Newtonian shear behavior with extremely high viscosityat low-shear to help avoid pigment settling and to ensure rapid and evenset-up of the coating immediately after application, but relatively lowviscosity at high shear rates to facilitate spraying and atomization ofthe spray into droplets.

A greater understanding of the coating composition described above andof the systems and method for applying the coating composition to thesubstrate utilizing the high transfer efficiency applicator may beobtained through a review of the illustrations accompanying thisapplication together with a review of the detailed description thatfollows.

With reference to FIG. 1 , a coating composition suitable forapplication to a substrate 10 utilizing a high transfer efficiencyapplicator 12 is provided herein. The coating composition exhibitsproperties rendering the coating composition suitable for applicationutilizing the high transfer efficiency applicator 12 including, but notlimited to, viscosity (η₀), density (φ, surface tension (σ), andrelaxation time (λ). Further, the coating composition as applied to thesubstrate 10 utilizing the high transfer efficiency applicator 12 formsa coating layer having precise boundaries, improved hiding, and reduceddrying time. In certain embodiments, the coating composition exhibitsnon-Newtonian fluid behavior which is in contrast to conventional ink.

Identifying suitable properties of the coating composition for use inthe high transfer efficiency applicator 12 may be dependent onproperties of the high transfer efficiency applicator 12. Properties ofthe high transfer efficiency applicator 12 may include, but are notlimited to, nozzle diameter (D) of the high transfer efficiencyapplicator 12, impact velocity (v) of the coating composition by thehigh transfer efficiency applicator 12, speed of the high transferefficiency applicator 12, distance of the high transfer efficiencyapplicator 12 from the substrate 10, droplet size of the coatingcomposition by the high transfer efficiency applicator 12, firing rateof the high transfer efficiency applicator 12, and orientation of thehigh transfer efficiency applicator 12 relative to the force of gravity.

In view of the various properties of the coating composition and thehigh transfer efficiency applicator 12, one or more relationships may beestablished between these properties for forming the coating compositionhaving properties suitable for application utilizing the high transferefficiency applicator 12. In various embodiments, various equations maybe applied to one or more of these properties of the coating compositionand the high transfer efficiency applicator 12 to determine boundariesfor these properties rendering the coating composition suitable forapplication utilizing the high transfer efficiency applicator 12. Incertain embodiments, the boundaries for the properties of the coatingcomposition may be determined by establishing an Ohnesorge number (Oh)for the coating composition, a Reynolds number (Re) for the coatingcomposition, a Deborah number (De) for the coating composition, orcombinations thereof.

In certain embodiments, the Ohnesorge number (Oh) is a dimensionlessconstant that generally relates to the tendency for a drop of thecoating composition, upon contact with the substrate, to either remainas a single drop or separate into many droplets (i.e., satellitedroplets), by considering viscous and surface tension forces of thecoating composition. The Ohnesorge number (Oh) may be determined inaccordance with equation I, as follows:

Oh=(η/√{square root over (ρσD)})  (I),

wherein η represents viscosity of the coating composition inpascal-seconds (Pa*s), ρ represents density of the coating compositionin kilograms per cubic meter (kg/m³), σ represents surface tension ofthe coating composition in newtons per meter (N/m), and D representsnozzle diameter of the high transfer efficiency applicator in meters(m). The Ohnesorge number (Oh) may be in a range of from about 0.01 toabout 50, alternatively from about 0.05 to about 10, or alternativelyfrom about 0.1 to about 2.70. The Ohnesorge number (Oh) may be at least0.01, alternatively at least 0.05, or alternatively at least 0.1. TheOhnesorge number (Oh) may be no greater than 50, alternatively nogreater than 10, or alternatively no greater than 2.70.

In various embodiments, the Reynolds number (Re) is a dimensionlessconstant that generally relates to the flow pattern of the coatingcomposition and, in certain embodiments, relates to flow patternsextending between laminar flow and turbulent flow by considering viscousand inertial forces of the coating composition. The Reynolds number (Re)may be determined in accordance with equation II, as follows:

Re=(ρvD/η)  (II),

wherein ρ represents density of the coating composition in kg/m³, vrepresents impact velocity of the high transfer efficiency applicator inmeters per second (m/s), D represents nozzle diameter of the hightransfer efficiency applicator 12 in m, and η represents viscosity ofthe coating composition in Pa*s. The Reynolds number (Re) may be in arange of from about 0.01 to about 1,000, alternatively from about 0.05to about 500, or alternatively from about 0.34 to about 258.83. TheReynolds number (Re) may be at least 0.01, alternatively at least 0.05,or alternatively at least 0.34. The Reynolds number (Re) may be nogreater than 1,000, alternatively no greater than 500, or alternativelyno greater than 258.83.

In other embodiments, the Deborah number (De) is a dimensionlessconstant that generally relates to the elasticity of the coatingcomposition and, in certain embodiments, relates to structure of avisco-elastic material by considering relaxation time of the coatingcomposition. The Deborah number (De) may be determined in accordancewith equation III, as follows:

De=λ/√{square root over (ρD ³/σ)}  (III),

wherein λ represents relaxation time of the coating composition inseconds (s), ρ represents density of the coating composition in kg/m³, Drepresents nozzle diameter of the high transfer efficiency applicator 12in m, and σ represents surface tension of the coating composition inN/m. The Deborah number (De) may be in a range of from about 0.01 toabout 2,000, alternatively from about 0.1 to about 1,000, oralternatively from about 0.93 to about 778.77. The Deborah number (De)may be at least 0.01, alternatively at least 0.1, or alternatively atleast 0.93. The Deborah number (De) may be no greater than 2,000,alternatively no greater than 1,000, or alternatively no greater than778.77.

In other embodiments, the Weber number (We) is a dimensionless constantthat generally relates to fluid flows where there is an interfacebetween two different. The Weber number (We) may be determined inaccordance with equation IV, as follows:

We=(Dv ²ρ/σ  (IV),

wherein D represents nozzle diameter of the high transfer efficiencyapplicator 12 in m, v represents impact velocity of the high transferefficiency applicator in meters per second (m/s), ρ represents densityof the coating composition in kg/m³, and σ represents surface tension ofthe coating composition in N/m. The Deborah number (De) may be in arange of from greater than 0 to about 16,600, alternatively from about0.2 to about 1,600, or alternatively from about 0.2 to about 10. TheDeborah number (We) may be at least 0.01, alternatively at least 0.1, oralternatively at least 0.2. The Deborah number (De) may be no greaterthan 16,600, alternatively no greater than 1,600, or alternatively nogreater than 10.

In certain embodiments, a coating composition for application to asubstrate utilizing a high transfer efficiency applicator is providedherein. The coating composition includes a carrier and a binder. Thecoating composition may have an Ohnesorge number (Oh) of from about 0.01to about 12.6, alternatively from about 0.05 to about 1.8, oralternatively about 0.38. The coating composition may have a Reynoldsnumber (Re) of from about 0.02 to about 6,200, alternatively from about0.3 to about 660, or alternatively about 5.21. The coating compositionmay have a Deborah number (De) of from greater than 0 to about 1730,alternatively from greater than 0 to about 46, or alternatively about1.02. The coating composition may have a Weber number (We) of fromgreater than 0 to about 16,600, alternatively from about 0.2 to about1,600, or alternatively about 3.86.

In view of one or more of the equations described above, the coatingcomposition may have a viscosity (η) in an amount of from about 0.001 toabout 1, alternatively from about 0.005 to about 0.1, or alternativelyfrom about 0.01 to about 0.06, pascal-seconds (Pa·s). The coatingcomposition may have a viscosity (η) in an amount of at least 0.001,alternatively at least 0.005, or alternatively at least 0.01, Pa·s. Thecoating composition may have a viscosity (η) in an amount of no greaterthan 1, alternatively no greater than 0.1, or alternatively no greaterthan 0.06, Pa·s. The viscosity (η) may be determined in accordance withASTM D2196-15. The viscosity (η) is determined at a high shear viscosityof 10,000 reciprocal seconds (1/sec). Printing a non-Newtonian fluid isgenerally represented at the high shear viscosity of 10,000 1/sec.

Further, in view of one or more of the equations described above, thecoating composition may have a density (ρ) in an amount of from about700 to about 1500, alternatively from about 800 to about 1400, oralternatively from about 1030 to about 1200, kilograms per cubic meter(kg/m³). The coating composition may have a density (ρ) in an amount ofat least 700, alternatively at least 800, or alternatively at least1030, kg/m³. The coating composition may have a density (ρ) in an amountof no greater than 1500, alternatively no greater than 1400, oralternatively no greater than 1200, kg/m³. The density (ρ) may bedetermined in accordance with ASTM D1475.

Also, in view of one or more of the equations described above, thecoating composition may have a surface tension (σ) in an amount of fromabout 0.001 to about 1, alternatively from about 0.01 to about 0.1, oralternatively from about 0.024 to about 0.05, newtons per meter (N/m).The coating composition may have a surface tension (σ) in an amount ofat least 0.001, alternatively at least 0.01, or alternatively at least0.015, N/m. The coating composition may have a surface tension (σ) in anamount of no greater than 1, alternatively no greater than 0.1, oralternatively no greater than 0.05, N/m. The surface tension (σ) may bedetermined in accordance with ASTM D1331-14.

Moreover, in view of one or more of the equations described above, thecoating composition may have a relaxation time (λ) in an amount of fromabout 0.00001 to about 1, alternatively from about 0.0001 to about 0.1,or alternatively from about 0.0005 to about 0.01, seconds (s). Thecoating composition may have a relaxation time (λ) in an amount of atleast 0.00001, alternatively at least 0.0001, or alternatively at least0.01, s. The coating composition may have a relaxation time (λ) in anamount of no greater than 1, alternatively no greater than 0.1, oralternatively no greater than 0.01, s. The relaxation time (λ) may bedetermined by a stress relaxation test performed in a strain controlledrheometer. The viscoelastic fluid is held between parallel plates, andan instantaneous strain is applied to one side of the sample. The otherside is held constant while stress (proportional to torque) is beingmonitored. The resulting stress decay is measured as a function of timeyielding stress relaxation modulus (stress divided by applied strain).For many fluids, stress relaxation modulus decays in an exponentialfashion with relaxation time as the decay constant.

In certain embodiments, a coating composition for application to asubstrate 10 utilizing a high transfer efficiency applicator 12 isprovided herein. The coating composition includes a carrier and abinder. The coating composition may have a viscosity (η) of from about0.002 Pa*s to about 0.2 Pa*s, the coating composition may have a density(ρ) of from about 838 kg/m³ to about 1557 kg/m³, the coating compositionmay have a surface tension (σ) of from about 0.015 N/m to about 0.05N/m, and the coating composition may have a relaxation time (λ) of fromabout 0.0005 s to about 0.02 s.

In various embodiments, the coating composition may have a viscosity (η)of from about 0.005 Pa*s to about 0.05 Pa*s, the coating composition mayhave a density (ρ) of from about 838 kg/m³ to about 1557 kg/m³, thecoating composition may have a surface tension (σ) of from about 0.015N/m to about 0.05 N/m, and the coating composition may have a relaxationtime (λ) of from about 0.0005 s to about 0.02 s.

In various embodiments, boundaries are determined for at least one ofthe following parameters: viscosity (η) of the coating composition, thesurface tension (σ) of the coating composition, the density (ρ) of thecoating composition, the relaxation time (λ) of the coating composition,the nozzle diameter (D) of the high transfer efficiency applicator 12,and the impact velocity (v) of the high transfer efficiency applicator12 by analyzing the Ohnesorge number (Oh), the Reynolds number (Re), andthe Deborah number (De). In certain embodiments, the coating compositinghaving one or more of these properties within the determined boundariesresults in the coating composition being suitable for application to thesubstrate 10 utilizing the high transfer efficiency applicator 12.

With reference to FIG. 2 , the Ohnesorge number (Oh) and the intrinsicDeborah number (De) may be utilized to determine boundaries for at leastone of the following: viscosity (η) of the coating composition, thesurface tension (σ) of the coating composition, the density (ρ) of thecoating composition, the nozzle diameter (D) of the high transferefficiency applicator 12, and the relaxation time of the polymer (λ). Afirst chart 14 of FIG. 2 shows a general relationship between theOhnesorge number (Oh) and the Deborah number (De). The first chart 14includes an unsuitable zone 16 relating to properties of the coatingcomposition that may render the coating composition undesirable forapplication to the substrate 10 utilizing the high transfer efficiencyapplicator 12. These undesirable properties may include, but are notlimited to, an excessively long relaxation time, formation of satellitedroplets from the coating composition, and a too high shear viscosity.Further, the first chart 14 includes a suitable zone 18, adjacent to theundesirable zones 14 relating to properties of the coating compositionthat may render the coating composition suitable for application to thesubstrate 10 utilizing the high transfer efficiency applicator 12. Inthis embodiment, the suitable zone 18 for the Ohnesorge number (Oh)extends along the y-axis of the first chart 14 in a range of from about0.10 to about 2.70 and the suitable zone 18 for the Deborah number (De)extends along the x-axis of the first chart 14 in a range of from about0.93 to about 778.8. The Ohnesorge number (Oh) and the Deborah number(De) corresponding to the suitable zone 18 can be applied to equations Iand III, respectively, for determining the suitable properties for thecoating composition. It is to be appreciated that the ranges for theOhnesorge number (Oh) and the Deborah number (De) corresponding to thesuitable zone 18 may be narrowed by defining one or more of theviscosity (η) of the coating composition, the surface tension (σ) of thecoating composition, the density (ρ) of the coating composition, thenozzle diameter (D) of the high transfer efficiency applicator 12, orthe relaxation time (λ) of the coating composition.

With reference to FIG. 3 , the Ohnesorge number (Oh) and the Reynoldsnumber (Re) may be utilized to determine boundaries for at least one ofthe following: the density (ρ) of the coating composition, the nozzlediameter (D) of the high transfer efficiency applicator 12, the impactvelocity (v) of the high transfer efficiency applicator 12, the surfacetension (σ) of the coating composition, and the viscosity (η) of thecoating composition. A second chart 20 of FIG. 3 shows a generalrelationship between the Reynolds number (Re) and the Ohnesorge number(Oh). The second chart 20 includes an unsuitable zone 22 relating toproperties of the coating composition that may render the coatingcomposition undesirable for application to the substrate 10 utilizingthe high transfer efficiency applicator 12. These undesirable propertiesmay include, but are not limited to, a too viscous coating composition,insufficient energy by the high transfer efficiency applicator 12,formation of satellite droplets from the coating composition, andsplashing of the coating composition. Further, the second chart 20includes a suitable zone 24, adjacent to the undesirable zones 22relating to properties of the coating composition that may render thecoating composition suitable for application to the substrate 10utilizing the high transfer efficiency applicator 12. In thisembodiment, the suitable zone 24 for the Reynolds number (Re) extendsalong the x-axis of the second chart 20 in a range of from about 0.34 toabout 258.8 and the suitable zone 24 for the Ohnesorge number (Oh)extends along the y-axis of the second chart 20 in a range of from about0.10 to about 2.7. The Reynolds number (Re) and the Ohnesorge number(Oh) corresponding to the suitable zone 24 can be applied to equationsII and I, respectively, for determining the suitable properties for thecoating composition. It is to be appreciated that the ranges for theReynolds number (Re) and the Ohnesorge number (Oh) corresponding to thesuitable zone 24 may be narrowed by defining one or more of the impactvelocity of the print head (v), the density (ρ) of the coatingcomposition, the nozzle diameter (D) of the high transfer efficiencyapplicator 12, the surface tension (σ) of the coating composition, andthe viscosity (η) of the coating composition.

With reference to FIG. 4A, the Ohnesorge number (Oh) and the Reynoldsnumber (Re) may be utilized to determine boundaries for at least one ofthe following: the density (ρ) of the coating composition, the nozzlediameter (D) of the high transfer efficiency applicator 12, the impactvelocity (v) of the high transfer efficiency applicator 12, the surfacetension (σ) of the coating composition, and the viscosity (η) of thecoating composition. The plot of FIG. 4A shows a general relationshipbetween the Reynolds number (Re) and the Ohnesorge number (Oh). The plotof FIG. 4A includes an unsuitable zone 52 relating to properties of thecoating composition that may render the coating composition undesirablefor application to the substrate 10 utilizing the high transferefficiency applicator 12. These undesirable properties may include, butare not limited to, a too viscous coating composition, insufficientenergy by the high transfer efficiency applicator 12, formation ofsatellite droplets from the coating composition, and splashing of thecoating composition. Further, the plot of FIG. 4A includes a suitablezone 54, adjacent to the undesirable zones 52 relating to properties ofthe coating composition that may render the coating composition suitablefor application to the substrate 10 utilizing the high transferefficiency applicator 12.

In certain embodiments, with continued reference to FIG. 4A, theOhnesorge number (Oh) is from 0.01 to 12.6 and is defined based upon thefollowing equations V and VI, in view of the Reynolds number (Re),

Oh is no greater than 10{circumflex over( )}(−0.5006*log(Re)+1.2135)  (V), and

Oh is at least 0{circumflex over ( )}(−0.5435*log(Re)−1.0324)  (VI),

wherein the Reynolds number (Re) is from 0.02 to 6,200. Equations V andVI can be utilized to define boundary 56 in the plot of FIG. 4A betweenthe undesirable zones 22 and the suitable zone 24.

In other embodiments, with continued reference to FIG. 4A, the Ohnesorgenumber (Oh) is from 0.05 to 1.8 and is defined based upon the followingequations VII and VIII, in view of the Reynolds number (Re),

Oh is no greater than 10{circumflex over( )}(−0.5067*log(Re)+0.706)  (VII), and

Oh is at least 10{circumflex over ( )}(−0.5724*log(Re)−0.4876)  (VIII),

wherein the Reynolds number (Re) is from 0.3 to 660. Equations VII andVIII can be utilized to further define boundary 58 in the plot of FIG.4A within the suitable zone 24.

With reference to FIG. 4B, the Ohnesorge number (Oh) and the Reynoldsnumber (Re) of various exemplary coating compositions are plotted alongwith the boundaries 56 and 58 of FIG. 4A thereby further showing therelevance of the boundaries 56 and 58.

In certain embodiments, a coating composition that is suitable forapplication utilizing the high transfer efficiency application 12exhibits minimal to no splashing at contact with the substrate 10. Thecoating composition exhibiting minimal to no splashing via applicationby the high transfer efficiency application 12 satisfies the followingequation IX,

0<v*D<0.0021 m²/s  (IX),

wherein v represents impact velocity as defined above and D representsthe nozzle diameter as defined above.

With reference to FIG. 5A, the Ohnesorge number (Oh) and the Reynoldsnumber (Re), in view of equation (IX), may be utilized to determineboundaries for at least one of the following: the density (ρ) of thecoating composition, the nozzle diameter (D) of the high transferefficiency applicator 12, the impact velocity (v) of the high transferefficiency applicator 12, the surface tension (σ) of the coatingcomposition, and the viscosity (η) of the coating composition. The plotof FIG. 5A shows a general relationship between the Reynolds number (Re)and the Ohnesorge number (Oh). The plot of FIG. 5A includes anunsuitable zone 60 relating to properties of the coating compositionthat may render the coating composition undesirable for application tothe substrate 10 utilizing the high transfer efficiency applicator 12.These undesirable properties may include, but are not limited to, a tooviscous coating composition, insufficient energy by the high transferefficiency applicator 12, formation of satellite droplets from thecoating composition, and splashing of the coating composition. Further,the plot of FIG. 5A includes a suitable zone 62, adjacent to theundesirable zones 60 relating to properties of the coating compositionthat may render the coating composition suitable for application to thesubstrate 10 utilizing the high transfer efficiency applicator 12.

In certain embodiments, with continued reference to FIG. 5A, theOhnesorge number (Oh) is from 0.01 to 12.6 and is defined based upon theequations V and VI above, in view of the Reynolds number (Re), whereinthe Reynolds number (Re) is from 0.02 to 1,600. equations V and VI canbe utilized to define boundary 64 in the plot of FIG. 5A between theundesirable zones 22 and the suitable zone 24.

In other embodiments, with continued reference to FIG. 5A, the Ohnesorgenumber (Oh) is from 0.05 to 1.8 and is defined based upon the equationsVII and VIII above, in view of the Reynolds number (Re), wherein theReynolds number (Re) is from 0.3 to 660. Equations VII and VIII can beutilized to further define boundary 66 in the plot of FIG. 5A within thesuitable zone 24.

With reference to FIG. 5B, the Ohnesorge number (Oh) and the Reynoldsnumber (Re) of various exemplary coating compositions are plotted alongwith the boundaries 64 and 64 of FIG. 5A thereby further showing therelevance of the boundaries 64 and 66.

A method of forming a coating composition for application to thesubstrate 10 utilizing the high efficiency transfer applicator 12 isprovided herein. The method includes the step of identifying at leastone of an Ohnesorge number (Oh) for the coating composition, a Reynoldsnumber (Re) for the coating composition, or a Deborah number (De) forthe coating composition. The method further includes the step ofobtaining at least one of a viscosity (η) of the coating composition, asurface tension (σ) of the coating composition, a density (ρ) of thecoating composition, a relaxation time (λ) of the coating composition, anozzle diameter (D) of the high efficiency transfer applicator 12, or animpact velocity (v) of the high efficiency transfer applicator 12.

At least one of the viscosity (η), the surface tension (σ), the density(ρ), or the nozzle diameter (D) is determined based upon the followingequation I in view of the Ohnesorge number (Oh),

Oh=(η/√{square root over (ρσD)})  (I).

At least one of the impact velocity (v), the density (ρ), the nozzlediameter D), or the viscosity (η) is determined based upon the followingequation II in view of the Reynolds number (Re).

Re=(ρvD/η)  (II).

At least one of the relaxation time (λ), the density (ρ), the nozzlediameter (D), or the surface tension (σ) is determined based upon thefollowing equation III in view of the Deborah number (De).

De=λ/√{square root over (ρD ³/σ)}  (III).

The method further includes the step of forming the coating compositionhaving at least one of the viscosity (η), the surface tension (σ), orthe density (ρ). The coating composition is configured to be applied tothe substrate 10 utilizing the high efficiency transfer applicator 12having at least one of the nozzle diameter (D) or the impact velocity(v).

In embodiments, the step of obtaining the viscosity (η) of the coatingcomposition further includes the step of performing a viscosity analysison the coating composition according to ASTM 7867-13 with cone-and-plateor parallel plates wherein, when the viscosity is from 2 to 200 mPa-s,the viscosity is measured at a 1000 sec−1 shear rate. In embodiments,the step of obtaining the surface tension (σ) of the coating compositionfurther includes the step of performing a surface tension analysis onthe coating composition according to ASTM 1331-14. In embodiments, thestep of obtaining the density (ρ) of the coating composition furtherincludes the step of performing a density analysis on the coatingcomposition according to ASTM D1475-13. In embodiments, the step ofobtaining the relaxation time (λ) of the coating composition furtherincludes the step of performing a relaxation time analysis on thecoating composition according to the methods described in Keshavarz B.et al. (2015) Journal of Non-Newtonian Fluid Mechanics, 222, 171-189 andGreiciunas E. et al. (2017) Journal of Rheology, 61, 467. Inembodiments, the step of obtaining the nozzle diameter (D) of the highefficiency transfer applicator further includes the step of measuring adiameter of a nozzle orifice of the high efficiency transfer applicator.In embodiments, the step of obtaining the impact velocity (v) of thedroplet expelled from the high efficiency transfer applicator furthercomprises the step of performing an impact velocity (v) analysis on thedroplet of the coating composition as the droplet is expelled from thehigh efficiency transfer applicator when the droplet is within 2millimeters distance from the substrate.

Another method of forming the coating composition for application to thesubstrate 10 utilizing the high transfer efficiency applicator 12 isalso provided herein. The method includes identifying a drop contactvalue that relates to the tendency for a drop of the coatingcomposition, upon contact with the substrate 10, to either remain as asingle drop or separate into many droplets, by considering viscous andsurface tension forces of the coating composition. The method furtherincludes identifying a flow pattern value that relates to the flowpattern of the coating composition extending between laminar flow andturbulent flow by considering viscous and inertial forces of the coatingcomposition. The method further includes identifying a fluidity valuethat relates to the fluidity of the coating composition extending beyondNewtonian viscous flow and non-Newtonian viscous flow by consideringrelaxation time of the coating composition. The coating composition isconfigured to be applied to the substrate 10 utilizing the high transferefficiency applicator 12 based on one or more of the drop contact value,the flow pattern value, and fluidity value.

In embodiments, the step of identifying the drop contact value includesthe step of identifying the Ohnesorge number (Oh) for the coatingcomposition. In embodiments, the step of identifying the flow patternvalue includes the step of identifying the Reynolds number (Re) for thecoating composition. In embodiments, the step of identifying thefluidity value includes the step of identifying the Deborah number (De)for the coating composition.

A method for determining suitability of the coating composition forapplication to the substrate 10 utilizing the high transfer efficiencyapplicator 12 is also provided herein. The method may be useful forstudying the effects of shear viscosity and extensional relaxation ondroplet formation. The method includes the step of providing the coatingcomposition. The method further includes the step of forming a droplet26 of the coating composition. The method further includes dropping thedroplet 26 from an elevated position 28 to a specimen substrate 30spaced from the elevated position 28. The method further includes thestep of the capturing, with a camera, the droplet 26 as the droplet 26extends from the elevated position 28 toward the specimen substrate 30to form a specimen image 32. The method further includes the step offorming a specimen coating layer 34 on the specimen substrate 30. Themethod further includes the step of analyzing the droplet 26 duringextension on the specimen image 32 and the specimen coating layer 34 onthe specimen substrate 30.

With reference to FIGS. 7A, 7B, 8A, 8B, 9A, and 9B, in embodiments,various specimen coating compositions are analyzed to study the effectsof shear viscosity and extensional relaxation. With particular referenceto FIGS. 7A and 7B, a first specimen coating composition 44 has a 0.16Pa*s shear viscosity and a 0.001 s extensional relaxation time. Withparticular reference to FIGS. 8A and 8B, a second specimen coatingcomposition 46 has a 0.009 Pa*s shear viscosity and a 0.001 extensionalrelaxation time. With particular reference to FIGS. 9A and 9B, a thirdspecimen coating composition 48 has a 0.040 Pa*s shear viscosity and a0.0025 s extensional relaxation time. The specimen image 32 of FIG. 7Bcorresponding to the first specimen coating composition 44 of FIG. 7Ashows the resulting specimen coating layer 34 having moderate flow afterdeposition with moderate droplet placement accuracy, few stray dropletsfrom satellites, and no splashing. The specimen image 32 of FIG. 8Bcorresponding to the second specimen coating composition 46 of FIG. 8Ashows the resulting specimen coating layer 34 having excessive flowafter deposition, and splashing on impact with the substrate 10. Thespecimen image 32 of FIG. 9B corresponding to the third specimen coatingcomposition 48 of FIG. 9A shows the resulting specimen coating layer 34having improved droplet placement accuracy, minimal flow afterdeposition, near zero stray droplets from satellites, and no splashing.

The coating composition may be utilized to form a coating layer on thesubstrate 10. The coating layer may be utilized as a basecoat, aclearcoat, a color coat, a top coat, a single-stage coat, a mid coat, aprimer, a sealer, or combinations thereof. In certain embodiments, thecoating composition is utilized to form a basecoat coating layer.

The term “basecoat” refers to a coating that is opaque and provides mostof protection, color, hiding (also known as “opacity”) and visualappearance. A basecoat typically contains color pigments, effectpigments such as metallic flakes pigments, rheology control agent, UVabsorber and other coating additives. The term “basecoat coatingcomposition” refers to a coating composition that can be used to form abasecoat. The term “basecoat layer” refers to a coating layer form froma basecoat coating composition. A basecoat layer can be formed byapplying one or more layers of the same or different basecoat coatingcompositions. In automotive coatings, a substrate 10 is typically coatedwith a primer layer for protection and adhesion, then a basecoat layerover the primer layer, optionally a sealer on top of primer, for most ofprotection, color and most of visual appearance, and subsequently aclearcoat layer over the basecoat layer for further protection andvisual appearance. Sometimes, a single coating layer, referred to as“top coat” can be used to provide the function of both the basecoat andthe clearcoat. Additional coating layer can also be used. For example, ametal substrate can be treated with a phosphate material and coated withan electrocoat layer before applying the primer layer.

The term “mid coat” or “mid coat layer” refers to a colored non-opaquecoating positioned between a basecoat layer and a clearcoat layer in amulti-layer coating system. To achieve some unique and attractive colorsor visual effects, the automobile industry and other coating end useapplications can use multi-layer coatings having three or more coatinglayers instead of the traditional “basecoat and clearcoat” two-layercoating system. The multi-layer system can usually comprise at least afirst colored and opaque basecoat layer, a second non-opaque color coatdeposited over at least a portion of the basecoat layer, and a thirdclearcoat layer deposited over at least a portion of the secondnon-opaque color coating layer. The second non-opaque color coat istypically referred to as a mid coat layer, which contains coloredpigments. The mid coat is typically formulated to be non-opaque so thecolor of the basecoat underneath can be visible through the mid coat.

A system 50 for applying a first coating composition and a secondcoating composition is provided herein. The system 50 includes a firsthigh transfer efficiency applicator including a first nozzle and thefirst nozzle defining a first nozzle orifice 92. The system furtherincludes a second high transfer efficiency applicator 90 including asecond nozzle and the second nozzle defining a second nozzle orifice 94.The system 50 further includes a first reservoir in fluid communicationwith the first high transfer efficiency applicator and configured tocontain the first coating composition. The system 50 further includes asecond reservoir in fluid communication with the second high transferefficiency applicator 90 and configured to contain the second coatingcomposition. The system 50 further includes a substrate 10 defining atarget area. The first high transfer efficiency applicator is configuredto receive the first coating composition from the first reservoir andconfigured to expel the first coating composition through the firstnozzle orifice 92 to the target area of the substrate to form a firstcoating layer. The second high transfer efficiency applicator 90 isconfigured to receive the second coating composition from the secondreservoir and configured to expel the second coating composition throughthe second nozzle orifice 94 to the first coating layer to form a secondcoating layer.

In certain embodiments, the first coating composition includes abasecoat coating composition and the second coating composition includesa clearcoat coating composition. In other embodiments, the first coatingcomposition includes a binder and the second coating compositionincludes a crosslinker reactive with the binder, or the first coatingcomposition includes a crosslinker and the second coating compositionincludes a binder reactive with the crosslinker.

With reference to FIG. 14 , in embodiments, a primer coating layer 96 isformed from a primer coating composition and may be disposed on thesubstrate 10. The first coating layer 98 may be disposed on the primercoating layer 96 and the second coating layer 100 may be disposed on thefirst coating layer 98. The primer coating composition may be appliedutilizing a conventional atomizing applicator.

The substrate 10 may include a metal-containing material, aplastic-containing material, or a combination thereof. In certainembodiments, the substrate 10 is substantially non-porous. The term“substantially” as utilized herein means that at least 95%, at least96%, at least 97%, at least 98%, at least 99% of a surface of thecoating layer is free of pores. The coating composition may be utilizedto coat any type of substrate 10 known in the art. In embodiments, thesubstrate 10 is a vehicle, automobile, or automobile vehicle. “Vehicle”or “automobile” or “automobile vehicle” includes an automobile, such as,car, van, mini van, bus, SUV (sports utility vehicle); truck; semitruck; tractor; motorcycle; trailer; ATV (all terrain vehicle); pickuptruck; heavy duty mover, such as, bulldozer, mobile crane and earthmover; airplanes; boats; ships; and other modes of transport. Thecoating composition may also be utilized to coat substrates inindustrial applications such as buildings; fences; ceramic tiles;stationary structures; bridges; pipes; cellulosic materials (e.g.,woods, paper, fiber, etc.). The coating composition may also be utilizedto coat substrates in consumer products applications such as helmets;baseball bats; bicycles; and toys. It is to be appreciated that the term“substrate” as utilized herein can also refer to a coating layerdisposed on an article that is also considered a substrate.

The coating layer may have a solvent resistance of at least 5 double MEKrubs, alternatively at least 20 double MEK rubs, or alternatively atleast 20 double MEK rubs, on a nonporous substrate in accordance withASTM D4752.

The coating layer may have a film tensile modulus of at least 100 MPa,alternatively at least 100 MPa, or alternatively at least 200 MPa, inaccordance with ASTM 5026-15.

The coating layer formed from the coating composition including acrosslinker may have a crosslink density of at least 0.2 mmol/cm³,alternatively at least 0.5 mmol/cm³, or alternatively at least 1.0mmol/cm³, in accordance with ASTM D5026-15.

The coating layer may have a gloss value of at least 75, alternativelyat least 88, or alternatively at least 92, at a 20 degree specular anglein accordance with ASTM 2813.

The coating layer may have a gloss retention of at least 50%,alternatively at least 70%, or alternatively at least 90%, of theinitial gloss value after 2000 hours of weathering exposure inaccordance with ASTM D7869.

The coating layer may have a thickness of at least 5 microns,alternatively at least 15 microns, or alternatively at least 50 microns,in accordance with ASTM D7091-13.

A system 50 for applying the coating composition to the substrate 10utilizing the high transfer efficiency applicator 12 is also providedherein. The system 50 includes the high transfer efficiency applicator12 which may be any high transfer efficiency applicator known in the artso long as it is suitable for printing the coating composition. The hightransfer efficiency applicator 12 may be configured as continuous feed,drop-on-demand, or selectively both. The high transfer efficiencyapplicator 12 may apply the coating composition via valve jet,piezo-electric, thermal, acoustic, or ultrasonic membrane. The system 50may include more than one high transfer efficiency applicator 12 witheach configured to apply a different coating composition (e.g.,different colors, solid or effect pigments, basecoat or clearcoat).However, it is to be appreciated that a single high transfer efficiencyapplicator 12 may be utilized to apply a variety of different coatingcompositions.

With reference to FIGS. 10A, 10B, 10C, and 10D, in embodiments, the hightransfer efficiency applicator 12 is a piezoelectric applicator 68configured to apply the coating composition drop-on-demand. Thepiezoelectric applicator 68 includes a piezoelectric element 70configured to deform between a draw position, a rest position, and anapplication position. The piezoelectric applicator 68 further includesthe nozzle through which a droplet 74 of the coating composition isapplied. In FIG. 10A, the piezoelectric element 70 is in a restposition. In FIG. 10B, the piezoelectric element 70 is in a drawposition to draw in the coating composition from the reservoir. In FIG.10C, the piezoelectric element 70 is in an application position to expelthe coating composition from the piezoelectric applicator 68 therebyforming the droplet 74. FIG. 10D, the piezoelectric element 70 returnsto the rest position. In certain embodiments, the high transferefficiency applicator 12 may have a jetting frequency of from about 100to about 1,000,000 Hz, alternatively from about 10,000 Hz to about100,000 Hz, or alternatively from about 30,000 Hz to about 60,000 Hz.

The high transfer efficiency applicator 12 may include a nozzle defininga nozzle orifice. It is to be appreciated that each high transferefficiency applicator may include more than one nozzle, such as forapplying a coating composition including effect pigments which mayrequire a larger nozzle orifice. The nozzle orifice 72 may have a nozzlediameter (D) in an amount of from about 0.000001 to about 0.001,alternatively from about 0.000005 to about 0.0005, or alternatively fromabout 0.00002 to about 0.00018, meters (m). The nozzle orifice 72 mayhave a nozzle diameter (D) in an amount of at least 0.000001,alternatively at least 0.000005, or alternatively at least 0.00002. Thenozzle orifice 72 may have a nozzle diameter (D) in an amount of nogreater than 0.001, alternatively no greater than 0.0005, oralternatively no greater than 0.00018.

With reference to FIG. 11 , in embodiments, the high transfer efficiencyapplicator 12 includes a plurality of nozzles 72. The nozzles 72 areoriented perpendicular to the traverse direction by which the hightransfer efficiency applicator moves. As a result, the spacing of thedroplets 72 of the coating composition is similar to the spacing of thenozzles 72 to one another.

With reference to FIG. 12 , in embodiments, the high transfer efficiencyapplicator includes a plurality of nozzles 72. The nozzles 72 areoriented diagonal relative to the traverse direction by which the hightransfer efficiency applicator moves. As a result, the spacing of thedroplets 74 of the coating composition is decreased relative to thespacing of the nozzles 72 to one another.

With reference to FIG. 13 , in embodiments, four high transferefficiency applicators each include a plurality of nozzles 72. The fourhigh transfer efficiency applicators 12 cooperate to form a hightransfer efficiency applicators assembly 76. The nozzles 72 are orientedperpendicular relative to the traverse direction by which the hightransfer efficiency applicator moves. The four high transfer efficiencyapplicators are offset from one another such that the spacing betweennozzles 72 is reduced overall for the high transfer efficiencyapplicators assembly 76. As a result, the spacing of the droplets 74 ofthe coating composition is further decreased relative to the spacing ofthe nozzles 72 to one another.

In certain embodiments, a system 50 for applying a coating compositionto a substrate 10 utilizing a high transfer efficiency applicator 12 isprovided herein. The system 50 includes a high transfer efficiencyapplicator 12 including a nozzle. The nozzle defining a nozzle orificeand may have a nozzle diameter of from about 0.00002 m to about 0.0004m. The system 50 further includes a reservoir in fluid communicationwith the high transfer efficiency applicator 12 and configured tocontain the coating composition. The coating composition includes acarrier and a binder. The coating composition may have a viscosity offrom about 0.002 Pa*s to about 0.2 Pa*s, a density of from about 838kg/m3 to about 1557 kg/m3, a surface tension of from about 0.015 N/m toabout 0.05 N/m, and a relaxation time of from about 0.0005 s to about0.02 s. The high transfer efficiency applicator 12 is configured toreceive the coating composition from the reservoir and configured toexpel the coating composition through the nozzle orifice 72 to thesubstrate 10 to form a coating layer 78. It is to be appreciated thatranges for the nozzle diameter, viscosity, density, surface tension, andrelaxation time may be defined by any of the ranges described herein.

The high transfer efficiency applicator 12 may be configured to expelthe coating composition through the nozzle orifice 72 at an impactvelocity of from about 0.2 m/s to about 20 m/s. Alternatively, the hightransfer efficiency applicator 12 may be configured to expel the coatingcomposition through the nozzle orifice 72 at an impact velocity of fromabout 0.4 m/s to about 10 m/s. The nozzle orifice 72 may have a nozzlediameter of from about 0.00004 m to about 0.00025 m. The coatingcomposition may be expelled from the high transfer efficiency applicator12 as a droplet 74 having a particle size of at least 10 microns.

In certain embodiments, at least 80% of the droplets 74 of the coatingcomposition expelled from the high transfer efficiency applicator 12contact the substrate 10. In other embodiments, at least 85%,alternatively at least 90%, alternatively at least 95%, alternatively atleast 97%, alternatively at least 98%, alternatively at least 99%, oralternatively at least 99.9% of the droplets 74 of the coatingcomposition expelled from the high transfer efficiency applicator 12contact the substrate 10. Without being bound by theory, it is believedthat an increase in the number of droplets 74 contacting the substrate10 relative to the number of droplets 74 that do not contact thesubstrate 10 thereby entering the environment, improves efficiency ofapplication of the coating composition, reduces waste generation, andreduces maintenance of the system 10.

In certain embodiments, at least 80% of the droplets 74 of the coatingcomposition expelled from the high transfer efficiency applicator 12 aremonodispersed such that the droplets 74 have a particle sizedistribution of less than 20%. In other embodiments, at least 85%,alternatively at least 90%, alternatively at least 95%, alternatively atleast 97%, alternatively at least 98%, alternatively at least 99%, oralternatively at least 99.9% of the droplets 74 of the coatingcomposition expelled from the high transfer efficiency applicator 12 aremonodispersed such that the droplets 74 have a particle sizedistribution of less than 20%, alternatively less than 15%,alternatively less than 10%, alternatively less than 5%, alternativelyless than 3%, alternatively less than 2%, alternatively less than 1%, oralternatively less than 0.1%. While conventional applicators rely onatomization to form “a mist” of atomized droplets of a coatingcomposition having a dispersed particle size distribution, themonodispersed droplets 74 formed by the high transfer efficiencyapplicator 12 can be directed to the substrate 10 thereby resulting inan improved transfer efficiency relative to conventional applicators.

In certain embodiments, at least 80% of the droplets 74 of the coatingcomposition expelled from the high transfer efficiency applicator 12 tothe substrate 10 remain as a single droplet after contact with thesubstrate 10. In other embodiments, at least 85%, alternatively at least90%, alternatively at least 95%, alternatively at least 97%,alternatively at least 98%, alternatively at least 99%, or alternativelyat least 99.9% of the droplets 74 of the coating composition expelledfrom the high transfer efficiency applicator 12 to the substrate 10remain as a single droplet after contact with the substrate 10. Withoutbeing bound by theory, it is believed that splashing of the coatingcomposition resulting from impact with the substrate 10 can be minimizedor eliminated by applying the coating composition utilizing the hightransfer efficiency applicator 12.

In certain embodiments, at least 80% of the droplets 74 of the coatingcomposition expelled from the high transfer efficiency applicator 12 tothe substrate 10 remain as a single droplet after expulsion from thenozzle orifice 72 of the high transfer efficiency applicator 12. Inother embodiments, at least 85%, alternatively at least 90%,alternatively at least 95%, alternatively at least 97%, alternatively atleast 98%, alternatively at least 99%, or alternatively at least 99.9%of the droplets 74 of the coating composition expelled from the hightransfer efficiency applicator 12 to the substrate 10 remain as a singledroplet after expulsion from the nozzle orifice 72 of the high transferefficiency applicator 12. Without being bound by theory, it is believedthat the formation of satellite droplet can be reduced or eliminated byapplying the coating composition utilizing the high transfer efficiencyapplicator 12. With reference to FIG. 6 , in certain embodiments, impactvelocity and nozzle diameter have an impact on satellite dropletformation. Satellite droplet formation may be reduced by considering theimpact velocity and the nozzle diameter.

In certain embodiments, the coating layer is a substantially uniformlayer according to macroscopic analysis. The term “substantially” asutilized herein means that at least 95%, at least 96%, at least 97%, atleast 98%, at least 99% of a surface of the coating layer covers asurface of the substrate 10 or a surface of an intervening layer betweenthe substrate 10 and the coating layer. The phrase “macroscopicanalysis” as utilized herein means that the analysis of the coatinglayer is performed based on visualization without a microscope.

Another system 50 for applying a first coating composition and a secondcoating composition is provided herein. The system includes a first hightransfer efficiency applicator including a first nozzle and the firstnozzle defining a first nozzle orifice 92. The system further includes asecond high transfer efficiency applicator 90 including a second nozzleand the second nozzle defining a second nozzle orifice 94. The system 50further includes a first reservoir in fluid communication with the firsthigh transfer efficiency applicator and configured to contain the firstcoating composition. The system 50 further includes a second reservoirin fluid communication with the second high transfer efficiencyapplicator 90 and configured to contain the second coating composition.The system 50 further includes a substrate 10 defining a first targetarea 80 and a second target area 82. The first high transfer efficiencyapplicator is configured to receive the first coating composition fromthe first reservoir and configured to expel the first coatingcomposition through the first nozzle orifice 92 to the first target area80 of the substrate 10. The second high transfer efficiency applicator90 is configured to receive the second coating composition from thesecond reservoir and configured to expel the second coating compositionthrough the second nozzle orifice 94 to the second target area 82 of thesubstrate 10. In certain embodiments, the first target area 80 isadjacent the second target area 82.

In certain embodiments, the first high transfer efficiency applicatorincludes a plurality of the first nozzles 72 with each of the firstnozzles 72 defining the first nozzle orifice 92. In these embodiments,the second high transfer efficiency applicator 90 includes a pluralityof the second nozzles with each of the second nozzles defining thesecond nozzle orifice 94. The first high transfer efficiency applicator88 is configured to expel the first coating composition through each ofthe first nozzle orifice 92 s independent of one another and the secondhigh transfer efficiency applicator 90 is configured to expel the secondcoating composition through each of the second nozzle orifice 94 sindependent of one another.

In various embodiments, the substrate 10 includes a first end 84 and asecond end 86 with the first target area 80 of the substrate 10 and thesecond target area 82 of the substrate 10 disposed therebetween. Thefirst high transfer efficiency applicator 88 and the second hightransfer efficiency applicator 90 may be configured to move from thefirst end 84 to the second end 86. The first high transfer efficiencyapplicator 88 and the second high transfer efficiency applicator 90 maybe configured to expel the first coating composition and the secondcoating composition through the first nozzle orifice 92 and the secondnozzle orifice 94 along a single pass from the first end 84 to thesecond end 86.

A path may be defined extending between the first end and the secondend. The first high transfer efficiency applicator 88 and the secondhigh transfer efficiency applicator 90 are configured to move along thepath. The first high transfer efficiency applicator 88 and the secondhigh transfer efficiency applicator 90 are configured to expel the firstcoating composition and the second coating composition through the firstnozzle orifice 92 and the second nozzle orifice 94 during a single passalong the path.

With reference to FIG. 16 , in one exemplary embodiment, the firsttarget area 80 of the substrate 10 and a second target area 82 of thesubstrate 10 cooperate to form a camouflage pattern. The first hightransfer efficiency applicator 88 and the second high transferefficiency applicator 90 are configured to expel the first coatingcomposition and the second coating composition through the first nozzleorifice 92 and the second nozzle orifice 94 to the first target area 80and the second target area 82 to form a coating layer having thecamouflage pattern during the single pass.

With reference to FIG. 17 , in another exemplary embodiment, the firsttarget area 80 of the substrate 10 and a second target area 82 of thesubstrate 10 cooperate to form a two-tone pattern. The first hightransfer efficiency applicator 88 and the second high transferefficiency applicator 90 are configured to expel the first coatingcomposition and the second coating composition through the first nozzleorifice 92 and the second nozzle orifice 94 to the first target area 80and the second target area 82 to form a coating layer having thetwo-tone pattern during the single pass.

With reference to FIG. 18 , in yet another exemplary embodiment, thefirst target area 80 of the substrate 10 and a second target area 82 ofthe substrate 10 cooperate to form a striping pattern. The first hightransfer efficiency applicator 88 and the second high transferefficiency applicator 90 are configured to expel the first coatingcomposition and the second coating composition through the first nozzleorifice 92 and the second nozzle orifice 94 to the first target area 80and the second target area 82 to form a coating layer having thestriping pattern during the single pass.

With reference to FIG. 19 , in still another exemplary embodiment, thefirst target area 80 of the substrate 10 and a second target area 82 ofthe substrate 10 cooperate to form an irregular pattern. The first hightransfer efficiency applicator 88 and the second high transferefficiency applicator 90 are configured to expel the first coatingcomposition and the second coating composition through the first nozzleorifice 92 and the second nozzle orifice 94 to the first target area 80and the second target area 82 to form a coating layer having theirregular pattern during the single pass.

With reference to FIG. 15 , the first target area 80 of the substrate 10and a second target area 82 of the substrate 10 may cooperate to form arectangular array alternating between the first target area 80 and thesecond target area 82. The first high transfer efficiency applicator 88and the second high transfer efficiency applicator 90 may be configuredto expel the first coating composition and the second coatingcomposition through the first nozzle orifice 92 and the second nozzleorifice 94 to the first target area 80 and the second target area 82 toform the coating layer during the single pass. In embodiments, the firstcoating composition includes a pigment and the second coatingcomposition includes an effect pigment.

The pigment of the first coating composition may be a primary pigment.Non-limiting examples of suitable primary pigments include pigments withcoloristic properties useful in the present invention including: bluepigments including indanthrone blue Pigment Blue 60, phthalocyanineblues, Pigment Blue 15:1, 15:, 15:3 and 15:4, and cobalt blue PigmentBlue 28; red pigments including quinacridone reds, Pigment Red 122 andPigment Red 202, iron oxide red Pigment Red 101, perylene reds scarletPigment Red 149, Pigment Red 177, Pigment Red 178, and maroon PigmentRed 179, azoic red Pigment Red 188, and diketo-pyrrolopyrrol redsPigment red 255 and Pigment Red 264; yellow pigments including diarylideyellows Pigment Yellow 14, iron oxide yellow Pigment Yellow 42, nickeltitanate yellow Pigment Yellow 53, indolinone yellows Pigment Yellow 110and Pigment Yellow 139, monoazo yellow Pigment yellow 150, bismuthvanadium yellow pigment Pigment Yellow 184, disazo yellows PigmentYellow 128 and Pigment Yellow 155; orange pigments includingquinacridone orange pigments Pigment Yellow 49 and Pigment Orange 49,benzimidazolone orange pigment Pigment Orange 36; green pigmentsincluding phthalocyanine greens Pigment Green 7 and Pigment Green 36,and cobalt green Pigment Green 50; violet pigments includingquinacridone violets Pigment Violet 19 and Pigment Violet 42, dioxaneviolet Pigment Violet 23, and perylene violet Pigment Violet 29; brownpigments including monoazo brown Pigment Brown 25 and chrome-antimonytitanate Pigment Brown 24, iron chromium oxide Pigment Brown 29; whitepigments such as anatase and rutile titanium dioxide (TiO2) PigmentWhite 6; and black pigments including carbon blacks Pigment Black 6 andPigment Black 7, perylene black Pigment Black 32, copper chromate blackPigment Black 28.

The second coating composition may include an effect pigment. The effectpigment of the second coating composition is selected from the group ofmetallic flake pigments, mica-containing pigments, glass-containingpigments, and combinations thereof.

The second coating composition may include a functional pigment. Thefunctional pigment may be selected from the groups of a radar reflectivepigment, LiDAR reflective pigment, corrosion inhibiting pigment, andcombinations thereof.

The second coating composition may include a functional additiveconfigured to cooperate with the first coating composition to improveproperties of the coating composition. The functional additive may beselected from the groups of anti-sag agent, pH modifier, catalyst,surface tension modifier, solubility modifier, adhesion promoter, andcombinations thereof.

In embodiments, the plurality of the first nozzles of the first hightransfer efficiency applicator 88 are arranged in a linear configurationrelative to one another along a first axis and the plurality of thesecond nozzles of the second high transfer efficiency applicator 90 arearranged in a linear configuration relative to one another along asecond axis, and wherein the first axis and the second axis are parallelto each other. The first high transfer efficiency applicator 88 may becoupled to the second high transfer efficiency applicator 90. The firsthigh transfer efficiency applicator 88 and the second high transferefficiency applicator 90 may cooperate to form a high transferefficiency applicator assembly that is a unitary component.

Another system 50 for applying a coating composition is provided herein.The system 50 includes a first high transfer efficiency applicator 88including a first nozzle and the first nozzle defining a first nozzleorifice 92. The system further includes a second high transferefficiency applicator 90 including a second nozzle and the second nozzledefines a second nozzle orifice 94. The system 50 further includes areservoir in fluid communication with the first high transfer efficiencyapplicator 88 and the second high transfer efficiency applicator 90. Thereservoir is configured to contain the coating composition. The system50 includes a substrate 10 defining a first target area 80 and a secondtarget area 82. The first high transfer efficiency applicator 88 and thesecond high transfer efficiency applicator 90 are configured to receivethe coating composition from the reservoir and configured to expel thecoating composition through the first nozzle orifice 92 to the firsttarget area 80 of the substrate 10 and to expel the coating compositionthrough the second nozzle orifice 94 to the second target area 82 of thesubstrate 10.

The first high transfer efficiency applicator 88 includes a plurality ofthe first nozzles with each of the first nozzles defining the firstnozzle orifice 92. The second high transfer efficiency applicator 90includes a plurality of the second nozzles with each of the secondnozzles defining the second nozzle orifice 94. The first high transferefficiency applicator 88 is configured to expel the coating compositionthrough each of the first nozzle orifices 90 independent of one anotherand the second high transfer efficiency applicator 90 is configured toexpel the coating composition through each of the second nozzle orifices94 independent of one another.

The substrate 10 includes a first end and a second end with the firsttarget area 80 of the substrate 10 and the second target area 82 of thesubstrate 10 disposed therebetween. The first high transfer efficiencyapplicator 88 and the second high transfer efficiency applicator 90 areconfigured to move from the first end to the second end, and the firsthigh transfer efficiency applicator 88 and the second high transferefficiency applicator 90 are configured to expel the coating compositionthrough the first nozzle orifice 92 and the second nozzle orifice 94along a single pass from the first end to the second end.

A path is defined extending between the first end and the second end.The first high transfer efficiency applicator 88 and the second hightransfer efficiency applicator 90 are configured to move along the path.The first high transfer efficiency applicator 88 and the second hightransfer efficiency applicator 90 are configured to expel the coatingcomposition through the first nozzle orifice 92 and the second nozzleorifice 94 during a single pass along the path.

The first target area 80 of the substrate 10 and a second target area 82of the substrate 10 cooperate to form a rectangular array alternatingbetween the first target area 80 and the second target area 82. Thefirst high transfer efficiency applicator 88 and the second hightransfer efficiency applicator 90 are configured to expel the coatingcomposition through the first nozzle orifice 92 and the second nozzleorifice 94 to the first target area 80 and the second target area 82 toform a uniform coating layer during the single pass.

The plurality of the first nozzles of the first high transfer efficiencyapplicator 88 are arranged in a linear configuration relative to oneanother along a first axis and the plurality of the second nozzles ofthe second high transfer efficiency applicator 90 are arranged in alinear configuration relative to one another along a second axis. Thefirst axis and the second axis are parallel to each other.

The plurality of the first nozzles includes a first nozzle A and a firstnozzle B adjacent the first nozzle A. The first nozzle A and the firstnozzle B are spaced from each other in a nozzle distance. The pluralityof the second nozzles includes a second nozzle A adjacent the firstnozzle A. The first nozzle A and the second nozzle A are spaced fromeach other in a high transfer efficiency applicator distance. The hightransfer efficiency applicator distance is substantially the same as thefirst nozzle distance.

The plurality of the first nozzles and the plurality of second nozzlesare spaced relative to each other to form a rectangular array andwherein the plurality of the first nozzles and the plurality of secondnozzles are configured to alternate expelling of the coating compositionbetween adjacent first and second nozzles of the rectangular array toreduce sag of the coating composition.

In various embodiments, the high transfer efficiency applicator 12includes sixty nozzles aligned along a y-axis. However, it is to beappreciated that the print head 12 can include any number of nozzles.Each nozzle may be actuated independent of the other nozzles to applythe coating composition to the substrate 10. During printing,independent actuation of the nozzles can provide control for placementof each of the droplets of the coating composition on the substrate 10.

Two or more print heads 12 may be coupled together to form a print headassembly. In certain embodiments, the print heads 12 are alignedtogether such that the y-axis of each of the print heads 12 are parallelto the other y-axes. Further, the nozzles of each of the print heads 12may be aligned with each other along an x-axis, which is perpendicularto the y-axis, such that an “array” is formed. One nozzle may be equallyspaced from the other nozzles directly adjacent the one nozzle, relativeto the x-axis and the y-axis. This configuration of nozzles may besuitable for applying the same coating composition by each of the printheads 12 to the substrate 10 as the print head assembly moves along thex-axis. Without being bound by theory, it is believed that equal spacingof the nozzles, relative to both the x-axis and the y-axis, may resultin uniform application of the same coating composition on the substrate10. Uniform application of the same coating composition may be suitablefor single-color applications, two-tone color applications, and thelike.

Alternatively, one set of nozzles along a first y-axis may be closelyspaced to another set of nozzles relative to the spacing of each of thenozzles along the y-axis of a single high transfer efficiency applicator12. This configuration of nozzles may be suitable for applying differentcoating compositions by each of the high transfer efficiency applicators12 to the substrate 10. Different coating compositions utilized withinthe same high transfer efficiency applicator assembly may be suitablefor logos, designs, signage, striped, camouflage appearance, and thelike.

The nozzles of the high transfer efficiency applicator 12 may have anyconfiguration known in the art, such as linear, concave relative to thesubstrate 10, convex relative to the substrate 10, circular, and thelike. Adjustment of the configuration of the nozzles may be necessary tofacilitate cooperation of the high transfer efficiency applicator 12 tosubstrates having irregular configurations, such as vehicles includingmirrors, trim panels, contours, spoilers, and the like.

The high transfer efficiency applicator 12 may be configured to blendindividual droplets to form a desired color. The high transferefficiency applicator 12 may include nozzles to apply cyan coatingcompositions, magenta coating compositions, yellow coating compositions,and black coating compositions. The properties of coating compositionsmay be modified to promote blending. Further, agitation sources, such asair movement or sonic generators may be utilized to promote blending ofthe coating compositions. The agitation sources may be coupled to thehigh transfer efficiency applicator 12 or separate therefrom.

A system for applying a first coating composition, a second coatingcomposition, and a third coating composition is also provided herein.The system includes a first high transfer efficiency applicator 88including a first nozzle and the first nozzle defining a first nozzleorifice 92. The system includes a second high transfer efficiencyapplicator 90 including a second nozzle and the second nozzle defining asecond nozzle orifice 94. The system further includes a third hightransfer efficiency applicator including a third nozzle and the thirdnozzle defining a third nozzle orifice. The system further includes afirst reservoir in fluid communication with the first high transferefficiency applicator 88 and configured to contain the first coatingcomposition. The system further includes a second reservoir in fluidcommunication with the second high transfer efficiency applicator 90 andconfigured to contain the second coating composition. The system furtherincludes a third reservoir in fluid communication with the third hightransfer efficiency applicator and configured to contain the thirdcoating composition. The system further includes a substrate 10 defininga target area. The first high transfer efficiency applicator 88 isconfigured to receive the first coating composition from the firstreservoir and configured to expel the first coating composition throughthe first nozzle orifice 92 to the target area of the substrate 10. Thesecond high transfer efficiency applicator 90 is configured to receivethe second coating composition from the second reservoir and configuredto expel the second coating composition through the second nozzleorifice 94 to the target area of the substrate 10. The third hightransfer efficiency applicator is configured to receive the thirdcoating composition from the third reservoir and configured to expel thethird coating composition through the third nozzle orifice to the targetarea of the substrate 10.

In embodiments, the first coating composition exhibits a first colorspace, the second coating composition exhibits a second color space, andthe third coating composition exhibits a third color space. In certainembodiments, the first color space includes a cyan color space accordingto CMYK color model, the second color space includes a magenta colorspace according to CMYK color model, and the third color space includesa yellow color space according to CMYK color model. In otherembodiments, the first color space includes a red color space accordingto RGB color model, the second color space includes a green color spaceaccording to RGB color model, and the third color space includes a bluecolor space according to RGB color model.

One or more of the first coating composition, the second coatingcomposition, and the third coating composition may be expelled onanother of the first coating composition, the second coatingcomposition, and third coating composition for generating a color spacedifferent than the first color space, the second color space, and thethird color space. In embodiments, the target area defines a pluralityof sub-areas and wherein one or more of the first high transferefficiency applicator 88, the second high transfer efficiency applicator90, and the third high transfer efficiency applicator is configured toexpel one or more of the first coating composition, the second coatingcomposition, and the third coating composition to the one or more of theplurality of sub-areas to generate a halftone pattern of one or more ofthe first color space, the second color space, and the third colorspace.

The first high transfer efficiency applicator 88 may include a pluralityof the first nozzles with each of the first nozzles defining the firstnozzle orifice 92. The second high transfer efficiency applicator 90 mayinclude a plurality of the second nozzles with each of the secondnozzles defining the second nozzle orifice 94. The third high transferefficiency applicator may include a plurality of the third nozzles witheach of the third nozzles defining the third nozzle orifice. The firsthigh transfer efficiency applicator 88 may be configured to expel thefirst coating composition through each of the first nozzle orifice 92 sindependent of one another. The second high transfer efficiencyapplicator 90 may be configured to expel the second coating compositionthrough each of the second nozzle orifice 94 s independent of oneanother. The third high transfer efficiency applicator may be configuredto expel the third coating composition through each of the third nozzleorifices independent of one another.

The substrate 10 includes a first end and a second end with the targetarea of the substrate 10 disposed therebetween. The first high transferefficiency applicator 88, the second high transfer efficiency applicator90, and the third high transfer efficiency applicator may be configuredto move from the first end to the second end. The first high transferefficiency applicator 88, the second high transfer efficiency applicator90, and the third high transfer efficiency applicator may be configuredto expel the first coating composition, the second coating composition,and the third coating composition through the first nozzle orifice 92,the second nozzle orifice 94, and the third nozzle orifice along asingle pass from the first end to the second end.

A path may be defined extending between the first end and the secondend. The first high transfer efficiency applicator 88, the second hightransfer efficiency applicator 90, and the third high transferefficiency applicator may be configured to move along the path. Thefirst high transfer efficiency applicator 88, the second high transferefficiency applicator 90, and the third high transfer efficiencyapplicator may be configured to expel the first coating composition, thesecond coating composition, and the third coating composition throughthe first nozzle orifice 92, the second nozzle orifice 94, and the thirdnozzle orifice during a single pass along the path.

The first high transfer efficiency applicator 88, the second hightransfer efficiency applicator 90, and the third high transferefficiency applicator may be coupled together. In embodiments, the firsthigh transfer efficiency applicator 88, the second high transferefficiency applicator 90, and the third high transfer efficiencyapplicator cooperate to form a high transfer efficiency applicatorassembly that is a unitary component.

In certain embodiments, the system further includes one or moreadditional high transfer efficiency applicators.

Certain substrates, such as vehicles, may require application of acoating composition to specific portion of its substrate 1010.Conventional dark coating layers, such as black, may not adequatelyreflect the signal generated by LiDAR at about 920 nm thereby impairingthe LiDAR's ability to recognize the substrate 10 including the darkcoating layer. Further, metallic coating layers, such as silver, mayreflect the signal generated by the LiDAR in a direction away from theLiDAR thereby impairing the LiDAR's ability to recognize the substrate10 including the metallic coating layer.

In certain embodiments, the coating composition includesLiDAR-reflective pigment that, when formed into a coating layer, mayimprove recognition of the substrate 10 by LiDAR. The size of coatinglayer formed from the coating composition including LiDAR-reflectivepigment may be just large enough to be recognized by LiDAR while stillmaintaining the appearance provided by the conventional coating.Further, the coating composition including LiDAR-reflective pigment maybe applied to specific locations on the vehicle (e.g., bumper, roofline, hood, side panel, mirrors, etc.) that are relevant to recognitionby LiDAR while still maintaining the appearance provided by theconventional coating. The coating composition including LiDAR-reflectivepigment may be any coating composition, such as a basecoat or a clearcoat. The coating composition including LiDAR-reflective pigment may beapplied to the substrate 10 by the high transfer efficiency applicator12 in a pre-defined location without the need for masking the substrate10 and wasting a portion of the coating composition includingLiDAR-reflective pigment through low-transfer efficiency applicationmethods, such as conventional spray atomization.

The LiDAR-reflective pigment may impact one or more properties of thecoating composition. Adjustment of the properties of the coatingcomposition may be necessary to render the coating composition suitablefor application utilizing the high transfer efficiency applicator 12including, but not limited to, viscosity (η₀), density (ρ), surfacetension (σ), and relaxation time (λ). Further, adjustment of propertiesof the high transfer efficiency applicator 12 may be necessary to renderthe high transfer efficiency applicator 12 suitable for application,including, but not limited to, nozzle diameter (D) of the high transferefficiency applicator 12, impact velocity (v) of the coating compositionby the high transfer efficiency applicator 12, speed of the hightransfer efficiency applicator 12, distance of the high transferefficiency applicator 12 from the substrate 10, droplet size of thecoating composition by the high transfer efficiency applicator 12,firing rate of the high transfer efficiency applicator 12, andorientation of the high transfer efficiency applicator 12 relative tothe force of gravity.

In embodiments, the coating composition includes a radar reflectivepigment or a LiDAR reflective pigment. In certain embodiments, the radarreflective pigment or the LiDAR reflective pigment may include, but isnot limited to, Nickel manganese ferrite blacks (Pigment Black 30) andiron chromite brown-blacks (CI Pigment Green 17, CI Pigment Browns 29and 35). Other commercially available infrared reflective pigments arePigment Blue 28 Pigment Blue 36, Pigment Green 26, Pigment Green 50,Pigment Brown 33, Pigment Brown 24, Pigment Black 12 and Pigment Yellow53. The LiDAR reflective pigment may also be referred to as an infraredreflective pigment.

The coating composition includes the LiDAR reflective pigment in anamount of from about 0.1 wt. % to about 5 wt. % based on a total weightof the coating composition. In embodiments, the coating layer has areflectance at a wavelength from 904 nm to 1.6 microns. The substrate 10may define a target area and a non-target area adjacent the target area.The high transfer efficiency applicator may be configured to expel thecoating composition through the nozzle orifice 72 to the target area toform a coating layer having a reflectance at a wavelength from 904 nm to1.6 microns. The non-target area may be substantially free of thecoating layer.

In various embodiments, the substrate 10, such as the leading edge of avehicle, is susceptible to damage from stones and other debris on theroadway during operation. An anti-chip coating composition may beapplied to the substrate 10 by the high transfer efficiency applicator12 in a pre-defined location without the need for masking the substrate10 and wasting a portion of the anti-chip coating composition throughlow-transfer efficiency application methods, such as conventional sprayatomization.

The anti-chip coating composition may include elastomeric polymers andadditives resulting in a coating layer exhibiting increased stone chipresistance. The elastomeric polymers and additives may impact one ormore properties of the coating composition. Adjustment of the propertiesof the coating composition may be necessary to render the coatingcomposition suitable for application utilizing the high transferefficiency applicator 12 including, but not limited to, viscosity (η₀),density (ρ), surface tension (σ), and relaxation time (λ). Further,adjustment of properties of the high transfer efficiency applicator 12may be necessary to render the high transfer efficiency applicator 12suitable for application, including, but not limited to, nozzle diameter(D) of the high transfer efficiency applicator 12, impact velocity (v)of the coating composition by the high transfer efficiency applicator12, speed of the high transfer efficiency applicator 12, distance of thehigh transfer efficiency applicator 12 from the substrate 10, dropletsize of the coating composition by the high transfer efficiencyapplicator 12, firing rate of the high transfer efficiency applicator12, and orientation of the high transfer efficiency applicator 12relative to the force of gravity.

In embodiments, the coating composition includes a binder including anelastomeric resin in an amount of at least 50 weight %, wherein theelastomeric resin has an Elongation to Break of at least 500% accordingto DIN 53 504. The binder may have a Tg of less than 0° C. In certainembodiments, the elastomeric resin is selected from the group of theelastomer is selected from the group of polyesters, polyurethanes,acrylics, and combinations thereof.

In embodiments, the coating layer has a chip resistance of at least4B/7C according to SAE J400. Alternatively, the coating layer has a chipresistance of at least 5B/8C according to SAE J400. The substrate 10 maydefine a target area and a non-target area adjacent the target area. Thehigh transfer efficiency applicator may be configured to expel thecoating composition through the nozzle orifice 72 to the target area toform a coating layer having a chip resistance of at least 4B/7Caccording to SAE J400. The non-target area is substantially free of thecoating layer. The analysis under SAE J400 is performed on a multilayercoating systems including primer, basecoat and clearcoat. In total thecomposite layering system is tested for mechanical integrity by applyingchip resistance damage by stones or other flying objects. Following themethod of SAE J400 (alternatively ASTM D-3170) using 2 kg of stone withdiameter 8-16 mm, where both stone and test panels have been conditionedto −20° F. (−29° C.+/−2°), stones are projected to the test panel with900 orientation using pressurized air at 70 psi (480 kPa+/−20) in timeperiod less than 30 sec. After pulling tape to remove loose paint chips,the damage is assessed using a visual scale.

In various embodiments, the substrate 10 is susceptible to damage fromcorrosion. Although modern substrates include an electrocoat layer toprevent corrosion on interior and exterior surfaces of vehicles, anadditional corrosion protection coating composition may be applied tothe substrate 10 by the high transfer efficiency applicator 12 in apre-defined location without the need for masking the substrate 10 andwasting a portion of the corrosion protection coating compositionthrough low-transfer efficiency application methods, such asconventional spray atomization.

The corrosion protection coating composition may include pigments oradditives that may impact one or more properties of the coatingcomposition. Adjustment of the properties of the coating composition maybe necessary to render the coating composition suitable for applicationutilizing the high transfer efficiency applicator 12 including, but notlimited to, viscosity (η₀), density (ρ), surface tension (σ), andrelaxation time (λ). Further, adjustment of properties of the hightransfer efficiency applicator 12 may be necessary to render the hightransfer efficiency applicator 12 suitable for application, including,but not limited to, nozzle diameter (D) of the high transfer efficiencyapplicator 12, impact velocity (v) of the coating composition by thehigh transfer efficiency applicator 12, speed of the high transferefficiency applicator 12, distance of the high transfer efficiencyapplicator 12 from the substrate 10, droplet size of the coatingcomposition by the high transfer efficiency applicator 12, firing rateof the high transfer efficiency applicator 12, and orientation of thehigh transfer efficiency applicator 12 relative to the force of gravity.

In embodiments, the coating composition further includes a corrosioninhibiting pigment. Any corrosion inhibiting pigment known in the artmay be utilized such as Calcium Strontium Zinc Phosphosilicate. In otherembodiments, double orthophosphates, in which one of the cations isrepresented by zinc can be used. For example, these may include Zn—Al,Zn—Ca, but also Zn—K, Zn—Fe, Zn—Ca—Sr or Ba—Ca and Sr—Ca combinations.It is possible to combine a phosphate anion with further anticorrosivelyefficient anions, such as silicate, molybdate, or borate. Modifiedphosphate pigments can be modified by organic corrosion inhibitors.Modified phosphate pigments can be exemplified by the followingcompounds: Aluminum(III) zinc(II) phosphate, Basic zinc phosphate, Zincphosphomolybdate, Zinc calcium phosphomolybdate, Zinc borophosphate.Moreover, Zinc strontium phosphosilicate, Calcium bariumphosphosilicate, Calcium strontium zinc phosphosilicate, andcombinations thereof. Zinc 5-nitroisophthalate, Calcium5-nitroisophthalate, Calcium cyanurate, metal salts ofdinonylnaphthalene sulfonic acids, and combinations thereof can also beused.

The coating composition may include the corrosion inhibiting pigment inan amount of from about 3 wt. % to about 12 wt. % based on a totalweight of the coating composition. In embodiments, the coating layer hasa corrosion resistance as demonstrated by no more than 10 mm creep fromscribe after 500 hours salt spray per ASTM B117. The substrate 10 maydefine a target area and a non-target area adjacent the target area. Thehigh transfer efficiency applicator may be configured to expel thecoating composition through the nozzle orifice 72 to the target area toform a coating layer having corrosion resistance as demonstrated by nomore than 10 mm creep from scribe after 500 hours salt spray per ASTMB117. The non-target area may be substantially free of the coatinglayer.

Various substrates may include two or more discrete portions ofdifferent materials. For example, vehicles can include metal-containingbody portions and plastic-containing trim portions. Due to the baketemperature limitations of plastics (80° C.) relative to metals (140°C.), the metal-containing body portions and the plastic-containing trimportions may be conventionally coated in separate facilities therebyincreasing the likelihood for mismatched coated parts. A coatingcomposition suitable for plastic substrates may be applied to theplastic substrates by the high transfer efficiency applicator 12 afterapplication and bake of the coating composition suitable for metalsubstrates without the need for masking the substrate 10 and wasting aportion of the coating composition through low-transfer efficiencyapplication methods, such as conventional spray atomization. The coatingcomposition suitable for plastic substrates may be applied using a firsthigh transfer efficiency applicator 88 12 and the coating compositionsuitable for metal substrates may be applied using a second hightransfer efficiency applicator 90 12. The first high transfer efficiencyapplicator 88 12 and the second high transfer efficiency applicator 9012 may form a high transfer efficiency applicator assembly.

The coating composition suitable for plastic substrates may includeisocyanate-based crosslinkers whereas the coating composition for metalsubstrates may include melamine-based crosslinkers. The crosslinkingtechnology of the coating composition may impact one or more propertiesof the coating composition. Adjustment of the properties of the coatingcomposition may be necessary to render the coating composition suitablefor application utilizing the high transfer efficiency applicator 12including, but not limited to, viscosity (η₀), density (ρ), surfacetension (σ), and relaxation time (λ). Further, adjustment of propertiesof the high transfer efficiency applicator 12 may be necessary to renderthe high transfer efficiency applicator 12 suitable for application,including, but not limited to, nozzle diameter (D) of the high transferefficiency applicator 12, impact velocity (v) of the coating compositionby the high transfer efficiency applicator 12, speed of the hightransfer efficiency applicator 12, distance of the high transferefficiency applicator 12 from the substrate 10, droplet size of thecoating composition by the high transfer efficiency applicator 12,firing rate of the high transfer efficiency applicator 12, andorientation of the high transfer efficiency applicator 12 relative tothe force of gravity.

A system for applying a first coating composition and a second coatingcomposition is provided herein. The system includes an atomizingapplicator. The system further includes a high transfer efficiencyapplicator comprising a nozzle and the nozzle defining a nozzle orifice.The system further includes a first reservoir in fluid communicationwith the atomizing applicator and configured to contain the firstcoating composition. The system further includes a second reservoir influid communication with the high transfer efficiency applicator andconfigured to contain the second coating composition. The system furtherincludes a substrate assembly comprising a metal-containing substrateand a plastic-containing substrate, the metal-containing substratecoupled to the plastic-containing substrate. The atomizing applicator isconfigured to receive the first coating composition from the firstreservoir and configured to apply the first coating composition to themetal-containing substrate. The high transfer efficiency applicator isconfigured to receive the second coating composition from the secondreservoir and configured to expel the second coating composition throughthe second nozzle orifice 94 to the plastic-containing substrate.

In embodiments, the atomizing applicator is configured to generate amist of atomized droplets of the first coating composition. In certainembodiments, the atomizing applicator includes a Bell spray applicator.However, it is to be appreciated that any conventional atomizing sprayapplicator may be utilized.

A method of applying a first coating composition and a second coatingcomposition utilizing an atomizing applicator and a high transferefficiency applicator is also provided herein. The high transferefficiency applicator includes a nozzle and the nozzle defines a nozzleorifice. The method includes the step of providing a substrate assemblyincluding a metal-containing substrate and a plastic-containingsubstrate. The metal-containing substrate may be coupled to theplastic-containing substrate. The method further includes the step ofapplying the first coating composition utilizing the atomizingapplicator to the metal-containing substrate. The method furtherincludes the step of applying the second coating composition through thenozzle orifice 72 of the high transfer efficiency applicator to theplastic-containing substrate.

The high transfer efficiency applicator 12 may be configured to applythe coating composition at an impact velocity (v) in an amount of fromabout 0.01 to about 100, alternatively from about 0.1 to about 50, oralternatively from about 1 to about 12, meters per second (m/s). Thehigh transfer efficiency applicator 12 may be configured to apply thecoating composition at an impact velocity (v) in an amount of at least0.01, alternatively at least 0.1, or alternatively at least 1, m/s. Thehigh transfer efficiency applicator 12 may be configured to apply thecoating composition at an impact velocity (v) in an amount of no greaterthan 100, alternatively no greater than 50, or alternatively no greaterthan 12, m/s.

The high transfer efficiency applicator 12 may further include areservoir in fluid communication with the high transfer efficiencyapplicator 12 and configured to contain the coating composition. Thereservoir may be directly couple to the high transfer efficiencyapplicator 12 or indirectly coupled to the high transfer efficiencyapplicator 12 via one or more tubes. More than one reservoir with eachof the reservoirs containing different coating compositions (e.g.,different colors, solid or effect pigments, basecoat or clearcoat, 2pack-coating compositions) may be coupled to the high transferefficiency applicator 12 for providing the different coatingcompositions to the same high transfer efficiency applicator 12. Thehigh transfer efficiency applicator 12 is configured to receive thecoating composition from the reservoir and configured to expel thecoating composition through the nozzle orifice 72 to the substrate 10.

A non-limiting example of the system 50 including the coatingcomposition and the high transfer efficiency applicator 12 may beconfigured to exhibit the following properties.

Properties Exemplary Minimum Exemplary Maximum Viscosity (η₀) of theabout 0.01 Pa · s about 0.06 Pa · s coating composition at (about 10 cP)(about 60 cP) 10,000 1/sec Density (ρ) of the about 0.00103 kg/m³ about0.00120 kg/m³ coating composition (about 8.6 lbs/gal) (about 10 lbs/gal)Surface Tension (σ) about 0.024 N/m about 0.05 N/m of the coating (about24 mN/m) (about 50 mN/m) composition Relaxation Time (λ) about 0.0005 sabout 0.01 s of the coating (about 0.5 msec) (about 10 msec) compositionNozzle Diameter (D) about 0.00002 m about 0.00018 m of the high transfer(about 20 μm) (about 180 μm) efficiency applicator 12 Impact Velocity(v) about 1 m/s about 12 m/s of the high transfer efficiency applicator12

When the coating composition is utilized to form the basecoat coatinglayer, a first basecoat layer having one color may be formed with asecond basecoat layer, disposed on the first basecoat layer, having asecond color. This configuration for the basecoat coating layer may beutilized for vehicles including two-tone colors (see FIG. 17 ), racingstripes, off-color panels such as the roof or hood, graphics, writing,or a combination thereof. However, it is to be appreciated that anysubstrate may benefit from such a configuration.

The first basecoat layer may be applied to the substrate 10 utilizing aconventional spraying apparatus, such as a Bell applicator, and thesecond basecoat layer may then be applied to the first basecoat layerutilizing the high transfer efficiency applicator 12. One or moreconsiderations can be used in this non-limiting example, such asconsidering the impact of the surface tension of the first basecoatlayer on the second basecoat layer. As a non-limiting example, thesurface tension of the first basecoat layer may be increased to improveflow of the coating composition as being applied to the first basecoatlayer utilizing the high transfer efficiency applicator 12. Thisimproved flow may be desirable when printing the coating composition ona full panel of a vehicle. As another non-limiting example, the surfacetension of the first basecoat layer may be decreased to improve improvedboundary retention and/or resolution of the coating composition as beingapplied to the first basecoat layer utilizing the high transferefficiency applicator 12. This improved boundary retention and/orresolution may be desirable when printing the coating composition as adesign, a writing, and the like. Further, one may consider the impact ofwet-on-wet application between the first basecoat layer and the secondbasecoat layer. For example, carrier selection and additive selectionmay have an effect on the suitability for the coating composition to beapplied to the first basecoat as a wet-on-wet application.

Other considerations may include print head speed of the high transferefficiency applicator 12, distance of the high transfer efficiencyapplicator 12 from the substrate 10, firing rate of the high transferefficiency applicator 12, and orientation of the substrate 10 relativeto gravity. Further considerations may relate to drying of the coatingcomposition after application to the substrate 10. Due to the lack ofatomization generated during application of the coating composition tothe substrate 10 utilizing the print head 12, drying components may beincluded in the system 50. Examples of suitable drying components mayinclude, but are not limited to, infrared lamps, ultraviolet lightlamps, forced air dryers, and the like. It is to be appreciated thatthese drying components may be coupled to the print head 12 or separatefrom the print head 12, but configured to cooperate with the print head12 to facilitate drying of the coating composition.

The coating composition includes various components, such as binders,pigments, extender pigments, dyes, rheology modifiers, carriers, such asorganic solvents, water, and non-aqueous solvents, catalysts,conventional additives, or combinations thereof. In embodiments thecarrier is selected from the group of water, a non-aqueous solvent, anda combination thereof. Conventional additives may include, but are notlimited to, dispersants, antioxidants, UV stabilizers and absorbers,surfactants, wetting agents, leveling agents, antifoaming agents,anti-cratering agents, or combinations thereof. In embodiments, thecoating composition is suitable for application to the substrate 10utilizing the high transfer efficiency applicator 12 on the basis thatthe coating composition includes certain components and/or includescertain components in a specific amount/ratio.

The term “binder” refers to film forming constituents of the coatingcomposition. Typically, a binder can include polymers, oligomers, or acombination thereof that are essential for forming a coating havingdesired properties, such as hardness, protection, adhesion, and others.Additional components, such as carriers, pigments, catalysts, rheologymodifiers, antioxidants, UV stabilizers and absorbers, leveling agents,antifoaming agents, anti-cratering agents, or other conventionaladditives may not be included in the term “binder” unless any of theseadditional components are film forming constituents of the coatingcomposition. One or more of those additional components can be includedin the coating composition. In certain embodiments, the binder includespolymers.

In embodiments, the polymer has a crosslinkable-functional group, suchas an isocyanate-reactive group. The term “crosslinkable-functionalgroup” refers to functional groups that are positioned in the oligomer,in the polymer, in the backbone of the polymer, in the pendant from thebackbone of the polymer, terminally positioned on the backbone of thepolymer, or combinations thereof, wherein these functional groups arecapable of crosslinking with crosslinking-functional groups (during thecuring step) to produce a coating in the form of crosslinked structures.Typical crosslinkable-functional groups can include hydroxyl, thiol,isocyanate, thioisocyanate, acetoacetoxy, carboxyl, primary amine,secondary amine, epoxy, anhydride, ketimine, aldimine, or a workablecombination thereof. Some other functional groups such as orthoester,orthocarbonate, or cyclic amide that can generate hydroxyl or aminegroups once the ring structure is opened can also be suitable ascrosslinkable-functional groups.

The coating composition may include a polyester-polyurethane polymer, alatex polymer, a melamine resin, or combinations thereof. It is to beappreciated that other polymers may be included in the coatingcomposition.

The polyester of the polyester-polyurethane polymer may be linear orbranched. Useful polyesters can include esterification products ofaliphatic or aromatic dicarboxylic acids, polyols, diols, aromatic oraliphatic cyclic anhydrides and cyclic alcohols. Non-limiting examplesof suitable cycloaliphatic polycarboxylic acids are tetrahydrophthalicacid, hexahydrophthalic acid, 1,2-cyclohexanedicarboxylic acid,1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,4-methylhexahydrophthalic acid, endomethylenetetrahydrophthalic acid,tricyclodecanedicarboxylic acid, endoethylenehexahydrophthalic acid,camphoric acid, cyclohexanetetracarboxylic, andcyclobutanetetracarboxylic acid. The cycloaliphatic polycarboxylic acidscan be used not only in their cis but also in their trans form and as amixture of both forms. Further non-limiting examples of suitablepolycarboxylic acids can include aromatic and aliphatic polycarboxylicacids, such as, for example, phthalic acid, isophthalic acid,terephthalic acid, halogenophthalic acids, such as, tetrachloro- ortetrabromophthalic acid, adipic acid, glutaric acid, azelaic acid,sebacic acid, fumaric acid, maleic acid, trimellitic acid, andpyromellitic acid. Combinations of polyacids, such as a combination ofpolycarboxylic acids and cycloaliphatic polycarboxylic acids can besuitable. Combinations of polyols can also be suitable.

Non-limiting suitable polyhydric alcohols include ethylene glycol,propanediols, butanediols, hexanediols, neopentylglycol, diethyleneglycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol,ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane,trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol,polyethylene glycol and polypropylene glycol. If desired, monohydricalcohols, such as, for example, butanol, octanol, lauryl alcohol,ethoxylated or propoxylated phenols may also be included along withpolyhydric alcohols to control the molecular weight.

Non-limiting examples of suitable polyesters include a branchedcopolyester polymer. The branched copolyester polymer and process forproduction described in U.S. Pat. No. 6,861,495, which is herebyincorporated by reference, can be suitable. Monomers withmultifunctional groups such as AxBy (x,y=1 to 3, independently) typesincluding those having one carboxyl group and two hydroxyl groups, twocarboxyl groups and one hydroxyl group, one carboxyl group and threehydroxyl groups, or three carboxyl groups and one hydroxyl group can beused to create branched structures. Non-limiting examples of suchmonomers include 2,3 dihydroxy propionic acid, 2,3 dihydroxy 2-methylpropionic acid, 2,2 dihydroxy propionic acid, 2,2-bis(hydroxymethyl)propionic acid, and the like.

The branched copolyester polymer can be conventionally polymerized froma monomer mixture containing a chain extender selected from the group ofa hydroxy carboxylic acid, a lactone of a hydroxy carboxylic acid, and acombination thereof; and one or more branching monomers. Some of thesuitable hydroxy carboxylic acids include glycolic acid, lactic acid,3-hydroxypropionic acid, 3-hydroxybutyric acid, 3-hydroxyvaleric acid,and hydroxypyvalic acid. Some of the suitable lactones includecaprolactone, valerolactone; and lactones of the corresponding hydroxycarboxylic acids, such as, e.g., 3-hydroxypropionic acid,3-hydroxybutyric acid, 3-hydroxyvaleric acid, and hydroxypyvalic acid.In certain embodiments, caprolactone can is utilized. In embodiments,the branched copolyester polymer can be produced by polymerizing, in onestep, the monomer mixture that includes the chain extender and hyperbranching monomers, or by first polymerizing the hyper branchingmonomers followed by polymerizing the chain extenders. It is to beappreciated that the branched copolyester polymer can be formed fromacrylic core with extending monomers described above.

The polyester-polyurethane polymer can be produced from the polyesterand polyisocyanates. The polyester can be polymeric or oligomericorganic species with at least two hydroxyl-functionalities ortwo-mercapto functionalities and their mixtures thereof. Polyesters andpolycarbonates with terminal hydroxy groups can be effectively used asthe diols.

The polyurethane polymers may be produced by reacting polyisocyanate(s)with polyol(s) in the excess. In certain embodiments, low molar masspolyols defined by an empirical and structural formula, such aspolyhydric alcohols are utilized to form the polyurethane polymer.Non-limiting examples of polyhydric alcohols include ethylene glycol,propanediols, butanediols, hexanediols, neopentylglycol, diethyleneglycol, cyclohexanediol, cyclohexanedimethanol, trimethylpentanediol,ethylbutylpropanediol, ditrimethylolpropane, trimethylolethane,trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol,polyethylene glycol and polypropylene glycol. In other embodiments,oligomeric or polymeric polyols with number-average molar masses of, forexample, up to 8000, alternatively up to 5000, alternative up to 2000,and/or, for example, corresponding hydroxyl-functional polyethers,polyesters or polycarbonates are utilized to form the polyurethanepolymer.

Non-limiting examples of suitable polyisocyanates include aromatic,aliphatic or cycloaliphatic di-, tri- or tetra-isocyanates, includingpolyisocyanates having isocyanurate structural units, such as, theisocyanurate of hexamethylene diisocyanate and isocyanurate ofisophorone diisocyanate; the adduct of two molecules of a diisocyanate,such as, hexamethylene diisocyanate and a diol such as, ethylene glycol;uretidiones of hexamethylene diisocyanate; uretidiones of isophoronediisocyanate or isophorone diisocyanate; the adduct of trimethylolpropane and meta-tetramethylxylene diisocyanate. Other polyisocyanatesdisclosed herein can also be suitable for producing polyurethanes.

Aqueous polyurethane binders and their production are well known to theskilled person. Typical and useful non-limiting examples of aqueouspolyurethane binders comprise aqueous polyurethane binder dispersionswhich can typically be made by first forming an NCO-functionalhydrophilic polyurethane prepolymer by addition reaction of polyol typecompounds and polyisocyanates, conversion of the so-formed polyurethaneprepolymer into the aqueous phase and then reacting the aqueouslydispersed NCO-functional polyurethane prepolymer with an NCO-reactivechain extender like, for example, a polyamine, a hydrazine derivative orwater. Such aqueous polyurethane binder dispersions as have been used asbinders in waterborne base coat compositions as are conventional in theproduction of base coat/clear coat two-layer coatings of car bodies andbody parts can be used in coating composition A; non-limiting examplesof aqueous polyurethane binder dispersions which can be used in coatingcomposition A can be found in U.S. Pat. Nos. 4,851,460, 5,342,882 and US2010/0048811 A1, which are expressly incorporated herein by reference.

One non-limiting example of a polyester-polyurethane polymer is apolyurethane dispersion resin formed from a linear polyester diol resin(reaction product of monomers 1,6-hexanediol, adipic acid, andisophthalic acid) and isophorone diisocyanate. Thispolyester-polyurethane polymer has a weight average molecular weight ofabout 30,000, a solids content of about 35 wt. %, and a particle size ofabout 250 nanometers.

Another non-limiting example of a polyester-polyurethane polymer is apolyurethane dispersion resin formed from a linearpolycarbonate-polyester and isophorone diisocyanate. Thispolyester-polyurethane polymer has a weight average molecular weight ofabout 75,000, a solids content of about 35 wt. %, and a particle size ofabout 180 nanometers.

In certain embodiments, the coating composition including thepolyester-polyurethane polymer may exhibit an increase in the elasticityof the coating composition as compared to a coating composition free ofthe polyester-polyurethane polymer. An increase in elasticity of thecoating composition may improve suitability of the coating compositionfor application to the substrate 10 utilizing the high transferefficiency applicator 12 by increasing relaxation time of the coatingcomposition. In various embodiments, the polyester-polyurethane polymerhaving the weight average molecular weight of 75,000, when included inthe coating composition, increases the relaxation time of the coatingcomposition as compared to a coating composition including thepolyester-polyurethane polymer having the weight average molecularweight of 30,000. It is to be appreciated that the relationship ofincreasing weight average molecular weight to increasing relaxation timeof the coating composition may not be limited to polyester-polyurethanepolymers. For example, polymers having weight average molecular weightsof at least 300,000, when incorporated into the coating composition, mayresult in the coating composition exhibiting an increased relaxationtime relative to a coating composition including the polymer with aweight average molecular weights of less than 300,000. It is further tobe appreciated that incorporation of at least minor concentrations ofhigh molecular weight polymers (e.g., at least 300,000) in the coatingcomposition may be used to improve suitability of the coatingcomposition by at least minimizing the formation of satellite droplet.

The coating composition may include the polyester-polyurethane polymerin an amount of from about 0.1 to about 50, alternatively from about 1to about 20, or alternatively from about 1 to about 10, wt. %, based ona total weight of the coating composition. In exemplary embodiments, thecoating composition includes a polyester-polyurethane polymer having thetradename Bayhydrol® U 241 which is commercially available from CovestroAG of Leverkusen, Germany.

The latex polymers, such as aqueous (meth)acryl copolymer latex bindersand their production, are well known to the skilled person. Aqueous(meth)acryl copolymer latex binders can typically be made byfree-radical emulsion copolymerization of olefinically unsaturatedfree-radically copolymerizable comonomers. For example, WO2006/118974A1, WO2008/124136 A1, WO2008/124137 A1 and WO2008/124141 A1, which areexpressly incorporated herein by reference, disclose aqueous (meth)acrylcopolymer latex binders and their use as binders in waterborne base coatcompositions as are conventional in the production of base coat/clearcoat two-layer coatings of car bodies and body parts. The aqueous(meth)acryl copolymer latex binders disclosed in WO2006/118974 A1,WO2008/124136 A1, WO2008/124137 A1 and WO2008/124141 A1, which areexpressly incorporated herein by reference, are non-limiting examples ofaqueous (meth)acryl copolymer latex binders which can be used in thecoating composition.

Melamine resins may be partially or fully etherified with one or morealcohols like methanol or butanol. A non-limiting example ishexamethoxymethyl melamine. Non-limiting examples of suitable melamineresins include monomeric melamine, polymeric melamine-formaldehyderesin, or a combination thereof. The monomeric melamines include lowmolecular weight melamines which contain, on an average, three or moremethylol groups etherized with a C₁ to C₅ monohydric alcohol such asmethanol, n-butanol, or isobutanol per triazine nucleus, and have anaverage degree of condensation up to about 2 and, in certainembodiments, in the range of from about 1.1 to about 1.8, and have aproportion of mononuclear species not less than about 50 percent byweight. By contrast the polymeric melamines have an average degree ofcondensation of more than about 1.9. Some such suitable monomericmelamines include alkylated melamines, such as methylated, butylated,isobutylated melamines and mixtures thereof. Many of these suitablemonomeric melamines are supplied commercially. For example, CytecIndustries Inc., West Patterson, N.J. supplies Cymel® 301 (degree ofpolymerization of 1.5, 95% methyl and 5% methylol), Cymel® 350 (degreeof polymerization of 1.6, 84% methyl and 16% methylol), 303, 325, 327,370 and XW3106, which are all monomeric melamines. Suitable polymericmelamines include high amino (partially alkylated, N, H) melamine knownas Resimene® BMP5503 (molecular weight 690, polydispersity of 1.98, 56%butyl, 44% amino), which is supplied by Solutia Inc., St. Louis, Mo., orCymel®1158 provided by Cytec Industries Inc., West Patterson, N.J. CytecIndustries Inc. also supplies Cymel® 1130@80 percent solids (degree ofpolymerization of 2.5), Cymel® 1133 (48% methyl, 4% methylol and 48%butyl), both of which are polymeric melamines.

The coating composition may include the melamine resin in an amount offrom about 0.1 to about 50, alternatively from about 1 to about 20, oralternatively from about 1 to about 10, wt. %, based on a total weightof the coating composition. In exemplary embodiments, the coatingcomposition includes a melamine-formaldehyde resin having the tradenameCymel® 303 which is commercially available from Cytec Industries Inc. ofWest Patterson, N.J.

The binder of the coating composition may further include a crosslinkingagent that can react with the crosslinkable-functional groups of thepolymers of the binder, to form a crosslinked polymeric network, hereinreferred to as a crosslinked network. It is to be appreciated that thecrosslinking agent is not necessary in all coating compositions, but maybe utilized in the coating composition to improve inter-coat adhesion,such as between the basecoat and the clearcoat, and for curing, such aswithin the clearcoat.

The term “crosslinking agent” refers to a component having“crosslinking-functional groups” that are functional groups positionedin each molecule of the compounds, oligomer, polymer, the backbone ofthe polymer, pendant from the backbone of the polymer, terminallypositioned on the backbone of the polymer, or a combination thereof,wherein these functional groups are capable of crosslinking with thecrosslinkable-functional groups (during the curing step) to produce acoating in the form of crosslinked structures. One of ordinary skill inthe art would recognize that certain combinations ofcrosslinking-functional group and crosslinkable-functional groups wouldbe excluded, since they would fail to crosslink and produce the filmforming crosslinked structures. The coating composition may include morethan one type of crosslinking agent that have the same or differentcrosslinking-functional groups. Typical crosslinking-functional groupscan include hydroxyl, thiol, isocyanate, thioisocyanate, acetoacetoxy,carboxyl, primary amine, secondary amine, epoxy, anhydride, ketimine,aldimine, orthoester, orthocarbonate, cyclic amide, or combinationsthereof.

Polyisocyanates having isocyanate-functional groups may be utilized asthe crosslinking agent to react with the crosslinkable-functionalgroups, such as hydroxyl-functional groups and amine-functional groups.In certain embodiments, only primary and secondary amine-functionalgroups may be reacted with the isocyanate-functional groups. Suitablepolyisocyanate can have on average 2 to 10, alternately 2.5 to 8, oralternately 3 to 8, isocyanate functionalities. Typically, the coatingcomposition has a ratio of isocyanate-functional groups on thepolyisocyanate to crosslinkable-functional group (e.g., hydroxyl and/oramine groups), of from about 0.25:1 to about 3:1, alternatively fromabout 0.8:1 to about 2:1, or alternatively from about 1:1 to about1.8:1. In other embodiments, melamine compounds havingmelamine-functional groups may be utilized as the crosslinking agent toreact with the crosslinkable-functional groups.

Non-limiting examples of suitable polyisocyanates include any of theconventionally used aromatic, aliphatic or cycloaliphatic di-, tri- ortetra-isocyanates, including polyisocyanates having isocyanuratestructural units, such as, the isocyanurate of hexamethylenediisocyanate and isocyanurate of isophorone diisocyanate; the adduct of2 molecules of a diisocyanate, such as, hexamethylene diisocyanate;uretidiones of hexamethylene diisocyanate; uretidiones of isophoronediisocyanate or isophorone diisocyanate; isocyanurate ofmeta-tetramethylxylylene diisocyanate; and a diol such as, ethyleneglycol.

Polyisocyanate-functional adducts having isocyanaurate structural unitscan also be used, for example, the adduct of 2 molecules of adiisocyanate, such as, hexamethylene diisocyanate or isophoronediisocyanate, and a diol such as ethylene glycol; the adduct of 3molecules of hexamethylene diisocyanate and 1 molecule of water(commercially available from Bayer Corporation of Pittsburgh, Pa. underthe trade name Desmodur® N); the adduct of 1 molecule of trimethylolpropane and 3 molecules of toluene diisocyanate (commercially availablefrom Bayer Corporation of Pittsburgh, Pa. under the trade name Desmodur®L); the adduct of 1 molecule of trimethylol propane and 3 molecules ofisophorone diisocyanate or compounds, such as 1,3,5-triisocyanatobenzene and 2,4,6-triisocyanatotoluene; and the adduct of 1 molecule ofpentaerythritol and 4 molecules of toluene diisocyanate.

The coating composition may include monomeric, oligomeric, or polymericcompounds that are curable by ultraviolet (UV), electron beam (EB),laser, and the like. Placement of a UV, EB, or laser source on the hightransfer efficiency applicator 12 may result in direct photo initiationof each droplet that is applied to the substrate 10 by the high transferefficiency applicator 12. The increase in use of monomers relative topolymers can increase the curable solids of the coating compositionwithout increasing the viscosity of the coating composition therebyreducing the volatile organic carbons (VOCs) released into theenvironment. However, the increase in use of monomers relative topolymers may impact one or more properties of the coating composition.Adjustment of the properties of the coating composition may be necessaryto render the coating composition suitable for application utilizing thehigh transfer efficiency applicator 12 including, but not limited to,viscosity (η₀), density (ρ), surface tension (σ), and relaxation time(λ). Further, adjustment of properties of the high transfer efficiencyapplicator 12 may be necessary to render the high transfer efficiencyapplicator 12 suitable for application, including, but not limited to,nozzle diameter (D) of the high transfer efficiency applicator 12,impact velocity (v) of the coating composition by the high transferefficiency applicator 12, speed of the high transfer efficiencyapplicator 12, distance of the high transfer efficiency applicator 12from the substrate 10, droplet size of the coating composition by thehigh transfer efficiency applicator 12, firing rate of the high transferefficiency applicator 12, and orientation of the high transferefficiency applicator 12 relative to the force of gravity.

A coating composition for application to a substrate 10 utilizing a hightransfer efficiency applicator is provided herein. The coatingcomposition includes monomeric, oligomeric, or polymeric compoundshaving a number average molecular weight of from about 400 to about20,000 and having a free-radically polymerizable double bond. Thecoating composition includes a photo initiator. The coating compositionhas an Ohnesorge number (Oh) of from about 0.01 to about 12.6. Thecoating composition has a Reynolds number (Re) of from about 0.02 toabout 6,200. The coating composition has a Deborah number (De) of fromgreater than 0 to about 1730.

The coating composition may include the monomeric, oligomeric, orpolymeric compounds in an amount of from about 20 wt. % to about 90 wt.% based on a total weight of the coating composition. The coatingcomposition may include the photo initiator in an amount of from about0.1 wt. % to about 2 wt. % based on a total weight of the coatingcomposition. It is to be appreciated that the coating compositionincluding the monomeric, oligomeric, or polymeric compounds may have upto 100% solids content based on a total weight of the coatingcomposition.

The high transfer efficiency applicator is configured to receive thecoating composition from the reservoir and configured to expel thecoating composition through the nozzle orifice 72 to the substrate 10 toform a coating layer. The coating layer may be formed in the presence ofhigh-energy radiation. The high-energy radiation may be generated by adevice configured to generate ultra violet light, a laser, an electronbeam, or combinations thereof. The device may be coupled to the hightransfer efficiency applicator and configured to direct the high-energyradiation toward the coating composition after expulsion through thenozzle orifice 72 of the high transfer efficiency applicator.

The coating compositions are waterborne, and include about 40 wt % toabout 90 wt % water, alternatively about 40 wt % to about 70 wt % water,based on the total weight of the composition. The film forming componentof the coating composition can include any UV curable water-dispersibleor latex polymer. A “latex” polymer means a dispersion of polymerparticles in water; a latex polymer typically requires a secondarydispersing agent (e.g., a surfactant) for creating a dispersion oremulsion of polymer particles in water. A “water-dispersible” polymermeans the polymer is itself capable of being dispersed into water (i.e.,without requiring the use of a separate surfactant) or water can beadded to the polymer to form a stable aqueous dispersion (i.e., thedispersion should have at least one month shelf stability at normalstorage temperatures). Such water-dispersible polymers can includenonionic or anionic functionality on the polymer, which assist inrendering them water-dispersible. For such polymers, external acids orbases are typically required for anionic stabilization.

Suitable UV curable polymers include, but are not limited to,polyurethanes, epoxies, polyamides, chlorinated polyolefins, acrylics,oil-modified polymers, polyesters, and mixtures or copolymers thereof.The UV curable polymers in the coating composition can include a widevariety of functional groups to modify their properties for a particularapplication, including, for example, acetoacetyl, (meth)acryl (wherein“(meth)acryl” refers to any of methacryl, methacrylate, acryl oracrylate), vinyl, vinyl ether, (meth)allyl ether (wherein (meth)allylether refers to an allyl ether and a methallyl ether), or mixturesthereof.

Acetoacetyl functionality may be incorporated into the UV curablepolymer through the use of: acetoacetoxyethyl acrylate,acetoacetoxypropyl methacrylate, allyl acetoacetate, acetoacetoxybutylmethacrylate, 2,3-di(acetoacetoxy)propyl methacrylate,2-(acetoacetoxy)ethyl methacrylate, t-butyl acetoacetate, diketene, andthe like, or combinations thereof. In general, any polymerizable hydroxyfunctional or other active hydrogen containing monomer can be convertedto the corresponding acetoacetyl functional monomer by reaction withdiketene or other suitable acetoacetylating agent (see, e.g., Comparisonof Methods for the Preparation of Acetoacetylated Coating Resins,Witzeman, J. S.; Dell Nottingham, W.; Del Rector, F. J. CoatingsTechnology; Vol. 62, 1990, 101 (and references contained therein)). Incoating compositions, the acetoacetyl functional group is incorporatedinto the polymer via 2-(acetoacetoxy)ethyl methacrylate, t-butylacetoacetate, diketene, or combinations thereof.

Coating compositions may incorporate a free radically polymerizablecomponent that includes at least one ingredient including free radicallypolymerizable functionality. Representative examples of free radicallypolymerizable functionality that is suitable include (meth)acrylategroups, olefinic carbon-carbon double bonds, allyloxy groups,alpha-methyl styrene groups, (meth)acrylamide groups, cyanate estergroups, (meth)acrylonitrile groups, vinyl ethers groups, combinations ofthese, and the like. The term “(meth)acryl”, as used herein, encompassesacryl and/or methacryl unless otherwise expressly stated. Acryl moietiesare may be utilized relative to methacryl moieties in many instances, asacryl moieties tend to cure faster.

Prior to initiating curing, free radically polymerizable groups mayprovide compositions with relatively long shelf life that resistpremature polymerization reactions in storage. At the time of use,polymerization can be initiated on demand with good control by using oneor more suitable curing techniques. Illustrative curing techniquesinclude but are not limited to exposure to thermal energy; exposure toone or more types of electromagnetic energy such as visible light,ultraviolet light, infrared light, or the like; exposure to acousticenergy; exposure to accelerated particles such as e-beam energy; contactwith chemical curing agents such as by using peroxide initiation withstyrene and/or a styrene mimetic; peroxide/amine chemistry; combinationsof these; and the like. When curing of such functionality is initiated,crosslinking may proceed relatively rapidly so resultant coatingsdevelop early green strength. Such curing typically proceedssubstantially to completion under wide range of conditions to avoidundue levels of leftover reactivity.

In addition to free radically polymerizable functionality, the freeradically polymerizable ingredient(s) incorporated into the freeradically polymerizable component may include other kinds offunctionality, including other types of curing functionality,functionality to promote particle dispersion, adhesion, scratchresistance, chemical resistance, abrasion resistance, combinations ofthese, and the like. For example, in addition to free radicallypolymerizable functionality, the free radically polymerizableingredient(s) may also include additional crosslinkable functionality toallow the composition to form an interpenetrating polymer network uponbeing cured. One example of such other crosslinkable functionalityincludes OH and NCO groups, which are co-reactive to form urethanelinkages. The reaction between OH and NCO often may be promoted by usinga suitable crosslinking agent and catalyst. To help disperse particleadditives, particularly ceramic particles, the ingredient(s) of the freeradically polymerizable component may include pendant dispersantmoieties such as acid or salt moieties of sulfonate, sulfate,phosphonate, phosphate, carboxylate, (meth)acrylonitrile, ammonium,quaternary ammonium, combinations of these, and the like. Otherfunctionality can be selected to promote adhesion, gloss, hardness,chemical resistance, flexibility, and the like. Examples include epoxy,slime, siloxane, alkoxy, ester, amine, amide, urethane, polyester;combinations of these, and the like.

The one or more free radically polymerizable ingredients incorporatedinto the free radically polymerizable component may be aliphatic and/oraromatic. For outdoor applications, aliphatic materials tend to showbetter weatherability.

The one or more free radically polymerizable ingredients incorporatedinto the free radically polymerizable component may be linear, branched,cyclic, fused, combinations of these, or the like. For instance,branched resins may be utilized in some instances, as these resins maytend to have lower viscosity than linear counterparts of comparablemolecular weight

In those embodiments in which the coating compositions are fluiddispersions, the free radically polymerizable component may function asat least a portion of the fluid carrier for particulate ingredients ofthe compositions. The coating compositions are as solvent-free aspractical such that the radiation curable component functions assubstantially the entirety of the fluid carrier. Some free radicallypolymerizable ingredients may, by themselves, exist as solids at roomtemperature, but tend to be readily soluble in one or more of the otheringredients used to provide the free radically polymerizable component.When cured, the resultant matrix serves as a binder for the otheringredients of the composition.

Illustrative embodiments of radiation curable components desirablyinclude a reactive diluent comprising one or more free radicallypolymerizable ingredients that have a weight average molecular weightunder about 750, alternatively in the range from about 50 to about 750,alternatively from about 50 to about 500. The reactive diluent functionsas a diluent, as an agent to reduce the viscosity of the coatingcomposition, as a coating binder/matrix when cured, as crosslinkingagents, and/or the like.

The radiation curable component also optionally includes at least onefree radically polymerizable resin in admixture with the reactivediluent. Generally, if the molecular weight of a resin is too large, thecompositions may tend to be too viscous for easy handling. This also canimpact the appearance of the resultant coating. On the other hand, ifthe molecular weight is too low, the toughness or resilience of theresultant compositions may suffer. It also can be more difficult tocontrol film thickness, and the resultant coatings may tend to be morebrittle than desired. Balancing these concerns, the term resin generallyencompasses free radically polymerizable materials having a weightaverage molecular weight of about 750 or greater, alternatively fromabout 750 to about 20,000, alternatively about 750 to about 10,000,alternatively about 750 to about 5000, and alternatively about 750 toabout 3000. Often, such one or more resins if solid by themselves atabout room temperature are soluble in the reactive diluent so that theradiation curable component is a single, fluid phase. As used herein,molecular weight refers to weight average molecular weight unlessotherwise expressly stated.

Desirably, the reactive diluent includes at least one ingredient that ismono functional with respect to free radically polymerizablefunctionality, at least one ingredient that is disfunctional withrespect to free radically polymerizable functionality, and at least oneingredient that is trifunctional or higher functionality with respect tofree radically polymerizable functionality. Reactive diluents includingthis combination of ingredients help to provide cured coatings withexcellent abrasion resistance while maintaining high levels oftoughness.

Representative examples of monofunctional, free radically polymerizableingredients suitable for use in the reactive diluent include styrene,alpha-methylstyrene, substituted styrene, vinyl esters, vinyl ethers,lactams such as N-vinyl-2-pyrrolidone, (meth)acrylamide, N-substituted(meth)acrylamide, octyl(meth)acrylate, nonylphenolethoxylate(meth)acrylate, isononyl(meth)acrylate,1,6-hexanediol(meth)acrylate, isobornyl(meth)acrylate,2-(2-ethoxyethoxy)ethyl(meth)acrylate, 2-ethylhexyl(meth)acrylate,lauryl(meth)acrylate, beta-carboxyethyl(meth)acrylate,isobutyl(meth)acrylate, cycloaliphatic epoxide, alpha-epoxide,2-hydroxyethyl(meth)acrylate, (meth)acrylonitrile, maleic anhydride,itaconic acid, isodecyl(meth)acrylate, dodecyl(meth)acrylate,n-butyl(meth)acrylate, methyl(meth)acrylate, hexyl(meth)acrylate,(meth)acrylic acid, N-vinylcaprolactam, stearyl(meth)acrylate, hydroxyfunctional caprolactone ester(meth)acrylate, octodecyl(meth)acrylate,isooctyl(meth)acrylate, hydroxyethyl(meth)acrylate,hydroxymethyl(meth)acrylate, hydroxypropyl(meth)acrylate,hydroxyisopropyl(meth)acrylate, hydroxybutyl(meth)acrylate,hydroxyisobutyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate,combinations of these, and the like. If one or more of suchmonofunctional monomers are present, these may comprise from 0.5 toabout 50, alternatively 0.5 to 35, and alternatively from about 0.5 toabout 25 weight percent of the radiation curable component based on thetotal weight of the free radically polymerizable component.

In some embodiments, a monofunctional component of the reactive diluentincludes a lactam having pendant free radically polymerizablefunctionality and at least one other ingredient that is monofunctionalwith respect to free radical polymerizability. At least one of suchadditional monofunctional ingredients has a weight average molecularweight in the range of from about 50 to about 500. The weight ratio ofthe lactam to the one or more other monofunctional ingredients desirablyis in the range from about 1:50 to 50:1, alternatively 1:20 to 20:1,alternatively about 2:3 to about 3:2. In one illustrative embodiment,using N-vinyl-2-pyrrolidone and octodecylacrylate at a weight ratio ofabout 1:1 would provide a suitable monofunctional component of thereactive diluent.

The di, tri, and/or higher functional constituents of the reactivediluent help to enhance one or more properties of the cured composition,including crosslink density, hardness, abrasion resistance, chemicalresistance, scratch resistance, or the like. In many embodiments, theseconstituents may include from 0.5 to about 50, alternatively 0.5 to 35,and alternatively from about 0.5 to about 25 weight percent of the freeradically polymerizable component based on the total weight of the freeradically polymerizable component. Examples of such higher functional,radiation curable monomers include ethylene glycol di(meth)acrylate,hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate,tetraethylene glycol di(meth)acrylate, trimethylolpropanetri(meth)acrylate (TMPTA), ethoxylated trimethylolpropanetri(meth)acrylate, glycerol tri(meth)acrylate, pentaerythritoltri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and neopentylglycol di(meth)acrylate, 1,6 hexanediol di(meth)acrylate,dipentaerythritol penta(meth)acrylate, combinations of these, and thelike. Additional free radically polymerizable monomers that would besuitable include those described in PCT Publication No. WO 02/077109.

In many embodiments, it is desirable if the reactive diluent includes atleast one trifunctional or higher functionality material having amolecular weight in the range from about 50 to about 500 to promoteabrasion resistance. The amount of such trifunctional or higherfunctionality materials used in the reactive diluent may vary over awide range. In many desirable embodiments, at least about 15 weightpercent, alternatively at least about 20 weight percent, at least about25 weight percent, and even at least 45 weight percent of the reactivediluent is at least trifunctional or higher with respect to freeradically polymerizable functionality based upon the total weight of thereactive diluent. These desirable embodiments incorporate an atypicallyhigh amount of tri- or higher functionality for increased crosslinkdensity and corresponding high hardness and scratch resistance, but yetshow excellent toughness.

Generally, one would expect that using so much crosslink density wouldobtain high hardness and scratch resistance at too much expense in termsof toughness and/or resilience. The conventional expectation would bethat the resultant compositions to be too brittle to be practical.However, a relatively large content of tri- or higher functionality canbe incorporated in the reactive diluent while still maintaining verygood levels of toughness and resilience. As discussed below, in someembodiments the diluent materials may be combined along with performanceenhancing free radically polymerizable resins, and various selectedparticles, including ceramic particles, organic particles, certain otheradditives, and combinations thereof.

The resultant free radically polymerizable components also haverheological properties to support relatively substantial particledistributions. This means that the free radically polymerizablecomponent can be loaded to very high levels with particles and otheradditives that help to promote desirable characteristics such as scratchresistance, toughness, durability, and the like. In many embodiments,the composite mixture of the free radically polymerizable materials andthe particle components may have pseudoplastic and thixotropicproperties to help control and promote smoothness, uniformity,aesthetics, and durability of the resultant cured compositions. Inparticular, the desirable thixotropic properties help reduce particlesettling after application. In other words, the free radicallypolymerizable component provides a carrier in which the particledistribution remains very stable during storage and after being appliedonto a substrate 10. This stability includes helping to maintainparticles at the composition surface to a large extent after applicationto a substrate 10. By maintaining particle populations at the surface,high scratch resistance at the surface is maintained.

In some embodiments, at least one of the constituents of the reactivediluent optionally includes epoxy functionality in addition to freeradically polymerizable functionality. In an illustrative embodiment, adiacrylate ingredient with a weight average molecular weight of about500 to 700 and including at least one backbone moiety derived from epoxyfunctionality is incorporated into the reactive diluent. One example ofsuch a material is commercially available under the trade designationCN120 from Sartomer Co., Inc. A blend containing 80 parts by weight ofthis oligomer with 20 parts by weight of TMPTA is also available fromthis source under the trade designation CN120C80. In some embodiments,using from about 1 to about 25, alternatively about 8 to 20 parts byweight of this oligomer per about 1 to about 50 parts by weight,alternatively 5 to 20 parts by weight of the monofunctional constituentsof the reactive diluent would be suitable. In an exemplary embodiment,using about 15 to 16 parts by weight of the CN120-80 admixture per about12 parts by weight of monofunctional ingredients would be suitable.

In addition to the reactive diluent, a free radically polymerizablecomponent may include one or more free radically polymerizable resins.When the free radically polymerizable component includes one or morefree radically polymerizable resins, the amount of such resinsincorporated into the compositions may vary over a wide range. Asgeneral guidelines the weight ratio of the free radically polymerizableresin(s) to the reactive diluent often may be in the range from about1:20 to about 20:1, alternatively 1:20 to 1:1, alternatively 1:4 to 1:1,and alternatively about 1:2 to 1:1.

In illustrative embodiments, the free radically polymerizable resincomponent desirably includes one or more resins such as (meth)acrylatedurethanes (i.e., urethane(meth)acrylates), (meth)acrylated epoxies(i.e., epoxy (meth)acrylates), (meth)acrylated polyesters (i.e.,polyester(meth)acrylates), (meth)acrylated(meth)acrylics,(meth)acrylated silicones, (meth)acrylated amines, (meth)acrylatedamides; (meth)acrylated polysulfones; (meth)acrylated polyesters,(meth)acrylated polyethers (i.e., polyether (meth)acrylates),vinyl(meth)acrylates, and (meth)acrylated oils. In practice, referringto a resin by its class (e.g., polyurethane, polyester, silicone, etc.)means that the resin includes at least one moiety characteristic of thatclass even if the resin includes moieties from another class. Thus, apolyurethane resin includes at least one urethane linkage but also mightinclude one or more other kinds of polymer linkages as well.

Representative examples of free radically polymerizable resin materialsinclude radiation curable (meth)acrylates, urethanes and urethane(meth)acrylates (including aliphatic polyester urethane (meth)acrylates)such as the materials described in U.S. Pat. Nos. 5,453,451, 5,773,487and 5,830,937. Additional free radically polymerizable resins that wouldbe suitable include those described in PCT Publication No. WO 02/077109.A wide range of such materials are commercially available.

Embodiments of the resin component include at least a first freeradically polymerizable polyurethane resin that has a glass transitiontemperature (Tg) of at least 500° C. and is at least trifunctional,alternatively at least tetrafunctional, alternatively at leastpentafunctional, and alternatively at least hexafunctional with respectto free radically polymerizable functionality. This first resindesirably has a Tg of at least about 600° C., alternatively at leastabout 800° C., and alternatively at least about 1000° C. In one mode ofpractice, a free radically polymerizable urethane resin having a Tg ofabout 500° C. to 60° C., and that is hexavalent with respect to(meth)acrylate functional would be suitable. An exemplary embodiment ofsuch a hexafunctional resin is commercially available under the tradedesignation Genomer 4622 from Rahn.

In some embodiments, the first resin is used in combination with one ormore other kinds of resins. Optionally, at least one of such otherresins is also free radically polymerizable. For example, someembodiments incorporate the first resin in combination with at least asecond free radically polymerizable resin that can be mono ormultifunctional with respect to free radically polymerizable moieties.If present, the second free radically polymerizable resin can have a Tgover a wide range, such as from −30° C. to 120° C. In some embodiments,the second resin has a Tg of less than 500° C., alternatively less thanabout 300° C., and alternatively than about 100° C. Many embodiments ofthe second resin are polyurethane materials. An exemplary embodiment ofsuch a resin is commercially available under the trade designationDesmolux U500 (formerly Desmolux XP2614) from Bayer MaterialSciencc AG.

Resins can be selected to achieve desired gloss objectives. For example,formulating a composition with a first free radically polymerizableresin having a relatively high Tg over about 500° C. in combination withan optional second free radically polymerizable resin having arelatively low Tg, such as below about 300° C., is helpful to providecoatings with mid-range gloss (e.g., about 50 to about 70) or high-rangegloss (greater than about 70). Formulating with only one or more freeradically polymerizable resins having a relatively higher Tg tends to behelpful to provide coatings with lower gloss (e.g., below about 50).

The weight ratio of the first and second resins may vary over a widerange. To provide coatings with excellent abrasion resistance andtoughness with respect to embodiments in which the Tg of the secondresin is under about 500° C., it is desirable if the ratio of thesecond, lower Tg resin to the first, higher Tg resin is in the rangefrom about 1:20 to 20:1, alternatively less than 1:1, such as in therange from about 1:20 to about 1:1, alternatively about 1:20 to about4:5, or alternatively about 1:20 to about 1:3. In one illustrativeembodiment, a weight ratio of about 9:1 would be suitable.

An exemplary embodiment of a free radically polymerizable componentcomprising a reactive diluent with an atypically high content oftrifunctional or higher functionality includes from about 1 to about 10,alternatively about 4 to about 8 parts by weight of a lactam such asN-vinyl-2-pyrrolidone, about 1 to about 10, alternatively about 2 toabout 8 parts by weight of another monofunctional material having amolecular weight under about 500 such as octodecyl acrylate, about 5 toabout 25, alternatively about 7 to about 30 parts by weight of adifunctional reactive diluent such as 1,6-hexane diacrylate; about 1 toabout 8, alternatively about 2 to 5 parts by weight of a trifunctionalreactive diluent having a molecular weight under about 500 such astrimethylol propane triacrylate TMPTA, about 1 to about 20 parts byweight of a trifunctional oligomer having a molecular weight in therange from about 500 to about 2000, about 1 to about 40 parts by weightof a difunctional oligomer having epoxy functionality and a molecularweight in the range from about 500 to about 2000, about 1 to about 15parts by weight of the first resin, and about 1 to about 15 parts byweight of the second resin.

In alternative embodiments, the coating includes a first coat whichprovides a colored illustration, such as a pattern, by the applicationof colored coatings with the aid of the high transfer efficiencyapplicator. A second, transparent coat consisting of one or morecovering layers (or top coats) is superposed on this first coat for thepurpose of protecting said first, colored coat.

In an embodiment, coating compositions are employed, including, forexample, pigments, oligomers, reactive diluents and other additivesfamiliar to the person skilled in the art. Suitable pigments are, forexample, Pigment Yellow 213, PY 151, PY 93, PY 83, Pigment Red 122, PR168, PR 254, PR 179, Pigment Red 166, Pigment Red 48:2, Pigment Violet19, Pigment Blue 15:1, Pigment Blue 15:3, Pigment Blue 15:4, PigmentGreen 7, Pigment Green 36, Pigment Black 7 or Pigment White 6. Suitableoligomers are, for example, aliphatic and aromatic urethane acrylates,polyether acrylates and epoxyacrylates, which acrylates may optionallybe monofunctional or polyfunctional, e.g. difunctional, trifunctional tohexafunctional, and decafunctional. Suitable reactive diluents are, forexample, dipropylene glycol diacrylate, tripropylene glycol diacrylate,tetrahydrofurfuryl acrylate, isobornyl acrylate and isodecyl acrylate.Further additives may be added to the inks for adjustment of theirproperties, such as, for example, dispersant additives, antifoams,photoinitiators, and UV absorbers.

In an embodiment, covering layers are employed. Suitable covering layersare, for example, products based on single-component (1K) ortwo-component (2K) isocyanate crosslinking systems (polyurethanes) orbased on 1K or 2K epoxy systems (epoxy resins). In certain embodiments,2K systems are employed. The covering layer employed according to theinvention can be transparent or translucent.

In two-component isocyanate crosslinking systems, isocyanates such as,for example, oligomers based on hexamethylene diisocyanate (HDI),diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), ortoluidine diisocyanate (TDI), e.g. isocyanurates, biuret, allophanates,and adducts of the isocyanates mentioned with polyhydric alcohols andmixtures thereof are employed as the curing component. Polyols such as,for example, OH group-containing polyesters, polyethers, acrylates andpolyurethane, and mixtures thereof, are employed as the bindingcomponent, which polyols may be solvent-based, solvent-free, orwater-dilutable.

In two-component epoxy systems, epoxy resins such as, for example,glycidyl ethers of bisphenols such as bisphenol A or bisphenol F andepoxidized aliphatic parent substances, and mixtures thereof, areemployed as the binding component. NH-functional substances such as, forexample, amines, amides and adducts of epoxy resins and amines, andmixtures thereof, are employed as the curing component.

In the case of polyol-containing binders, customary commercialisocyanate curing agents and in the case of epoxy resin-containingbinders, NH-functional curing agents can be employed as the curingcomponent.

The mixing ratios of the binder and curing components are selected suchthat the weights of the respective components, in each case based on theamount of substance of the reactive groups, are present in an OH:NCO orepoxy:NH ratio in the range of from 1:0.7 to 1:1.5, alternatively from1:0.8 to 1:1.2 or alternatively 1:1.

A 3-layer coating can be employed in various industrial sectors. Thebasecoat is formed by primers that can be applied to wood, metal, glass,and plastics materials. Examples of suitable primers for use areproducts based on single-component (1K) or two-component (2K) isocyanatecrosslinking systems (polyurethanes) or based on 1K or 2K epoxy systems(epoxy resins).

As introduced above, the coating composition may further includepigment. Any pigment known in the art for use in coating compositionsmay be utilized in the coating composition. Non-limiting examples ofsuitable pigments include metallic oxides, metal hydroxide, effectpigments including metal flakes, chromates, such as lead chromate,sulfides, sulfates, carbonates, carbon black, silica, talc, china clay,phthalocyanine blues and greens, organo reds, organo maroons,pearlescent pigments, other organic pigments and dyes, and combinationsthereof. If desired, chromate-free pigments, such as barium metaborate,zinc phosphate, aluminum triphosphate and combinations thereof, can alsobe utilized.

Further non-limiting examples of suitable effect pigments include brightaluminum flake, extremely fine aluminum flake, medium particle sizealuminum flake, and bright medium coarse aluminum flake; mica flakecoated with titanium dioxide pigment also known as pearl pigments; andcombinations thereof. Non-limiting examples of suitable colored pigmentsinclude titanium dioxide, zinc oxide, iron oxide, carbon black, mono azored toner, red iron oxide, quinacridone maroon, transparent red oxide,dioxazine carbazole violet, iron blue, indanthrone blue, chrometitanate, titanium yellow, mono azo permanent orange, ferrite yellow,mono azo benzimidazolone yellow, transparent yellow oxide, isoindolineyellow, tetrachloroisoindoline yellow, anthanthrone orange, leadchromate yellow, phthalocyanine green, quinacridone red, perylenemaroon, quinacridone violet, pre-darkened chrome yellow, thio-indigored, transparent red oxide chip, molybdate orange, molybdate orange red,and combinations thereof.

As also introduced above, the coating composition may further includeextender pigments. While extender pigments are generally utilized toreplace higher cost pigments in coating compositions, the extenderpigments as contemplated herein may increase shear viscosity of thecoating composition as compared to a coating composition free of theextender pigments. An increase in shear viscosity of the coatingcomposition may improve suitability of the coating composition forapplication to the substrate 10 utilizing the high transfer efficiencyapplicator 12. The extender pigment may have a particle size of fromabout 0.01 to about 44 microns. The extender pigment may have a varietyof configurations including, but not limited to, nodular, platelet,acicular, and fibrous. Non-limiting examples of suitable extenderpigments include whiting, barytes, amorphous silica, fumed silica,diatomaceous silica, china clay, calcium carbonate, phyllosilicate(mica), wollastonite, magnesium silicate (talc), barium sulfate, kaolin,and aluminum silicate.

The coating composition may include the extender pigment in an amount offrom about 0.1 to about 50, alternatively from about 1 to about 20, oralternatively from about 1 to about 10, wt. %, based on a total weightof the coating composition. In certain embodiments, the coatingcomposition includes magnesium silicate (talc), barium sulfate, or acombination thereof. In various embodiments, inclusion of barium sulfateas the extender pigment results in a coating composition having greatershear viscosity as compared to inclusion of talc as the extenderpigment.

As also introduced above, the coating composition may further includedyes. Non-limiting examples of suitable dyes include triphenylmethanedyes, anthraquinone dyes, xanthene and related dyes, azo dyes, reactivedyes, phthalocyanine compounds, quinacridone compounds, and fluorescentbrighteners, and combinations thereof. The coating composition mayinclude the dye in an amount of from about 0.01 to about 5,alternatively from about 0.05 to about 1, or alternatively from about0.05 to about 0.5, wt. %, based on a total weight of the coatingcomposition. In certain embodiments, the coating composition includes a10% black dye solution, such as Sol. Orasol Negro RL.

As also introduced above, the coating composition may further includerheology modifiers. Many different types of rheology modifiers can beused in coating compositions may be utilized in the coating composition.For example, a rheology modifier can be used that may increase rheologyof the coating composition as compared to a coating composition free ofthe rheology modifier. An increase in rheology of the coatingcomposition may improve suitability of the coating composition forapplication to the substrate 10 utilizing the high transfer efficiencyapplicator 12. Non-limiting examples of suitable rheology modifiersinclude urea-based compounds, laponite propylene glycol solutions,acrylic alkali emulsions, and combinations thereof. The coatingcomposition may include the rheology modifier in an amount of from about0.01 to about 5, alternatively from about 0.05 to about 1, oralternatively from about 0.05 to about 0.5, wt. %, based on a totalweight of the coating composition. In certain embodiments, the coatingcomposition includes the laponite propylene glycol solution, the acrylicalkali emulsion, or a combination thereof. The laponite propylene glycolsolution includes a synthetic layered silicate, water, and polypropyleneglycol. The synthetic layered silicate is commercially available fromAltana AG of Wesel, Germany under the trade name Laponite RD. Theacrylic alkali emulsion is commercially available from BASF Corporationof Florham Park, N.J. under the tradename Viscalex® HV 30.

As also introduced above, the coating composition may further includeorganic solvents. In embodiments, the coating composition is asolventborne coating composition when the organic solvent content isgreater than about 50 wt. %, alternatively greater than 60 wt. %,alternatively greater than 70 wt. %, alternatively greater than 80 wt.%, or alternatively greater than 90 wt. %, based on a total weight ofliquid carrier in the coating composition. Non-limiting examples ofsuitable organic solvents can include aromatic hydrocarbons, such as,toluene, xylene; ketones, such as, acetone, methyl ethyl ketone, methylisobutyl ketone, methyl amyl ketone and diisobutyl ketone; esters, suchas, ethyl acetate, n-butyl acetate, isobutyl acetate, and a combinationthereof. In embodiments, the evaporation rate of the solvent may have animpact on the suitability of the coating composition for printing.Certain co-solvents may be incorporated into the coating compositionhaving increased or decreased evaporation rates thereby increasing ordecreasing the evaporation rate of the coating composition.

As also introduced above, the coating composition may further includewater. In embodiments, the coating composition is a waterborne coatingcomposition when the water content is greater than about 50 wt. %,alternatively greater than 60 wt. %, alternatively greater than 70 wt.%, alternatively greater than 80 wt. %, or alternatively greater than 90wt. %, based on a total weight of liquid carrier in the coatingcomposition. The coating composition may have a pH of from about 1 toabout 14, alternatively from about 5 to about 12, or alternatively fromabout 8 to about 10.

As also introduced above, the coating composition may further include acatalyst. The coating composition may further include a catalyst toreduce curing time and to allow curing of the coating composition atambient temperatures. The ambient temperatures are typically referred toas temperatures in a range of from 18° C. to 35° C. Non-limitingexamples of suitable catalysts may include organic metal salts, such as,dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dichloride,dibutyl tin dibromide, zinc naphthenate; triphenyl boron, tetraisopropyltitanate, triethanolamine titanate chelate, dibutyl tin dioxide, dibutyltin dioctoate, tin octoate, aluminum titanate, aluminum chelates,zirconium chelate, hydrocarbon phosphonium halides, such as, ethyltriphenyl phosphonium iodide and other such phosphonium salts and othercatalysts, or a combination thereof. Non-limiting examples of suitableacid catalysts may include carboxylic acids, sulfonic acids, phosphoricacids or a combination thereof. In some embodiments, the acid catalystcan include, for example, acetic acid, formic acid, dodecyl benzenesulfonic acid, dinonyl naphthalene sulfonic acid, para-toluene sulfonicacid, phosphoric acid, or a combination thereof. The coating compositionmay include the catalysts in an amount of from about 0.01 to about 5,alternatively from about 0.05 to about 1, or alternatively from about0.05 to about 0.5, wt. %, based on a total weight of the coatingcomposition.

As also introduced above, the coating composition may further includeconventional additives. The coating composition may further include anultraviolet light stabilizer. Non-limiting examples of such ultravioletlight stabilizers include ultraviolet light absorbers, screeners,quenchers, and hindered amine light stabilizers. An antioxidant can alsobe added to the coating composition. Typical ultraviolet lightstabilizers can include benzophenones, triazoles, triazines, benzoates,hindered amines and mixtures thereof. A blend of hindered amine lightstabilizers, such as Tinuvin® 328 and Tinuvin®123, all commerciallyavailable from Ciba Specialty Chemicals of Tarrytown, N.Y., under thetrade name Tinuvin®, can be utilized.

Non-limiting examples of suitable ultraviolet light absorbers includehydroxyphenyl benzotriazoles, such as,2-(2-hydroxy-5-methylphenyl)-2H-benzotrazole,2-(2-hydroxy-3,5-di-tert.amyl-phenyl)-2H-benzotriazole,2[2-hydroxy-3,5-di(1,1-dimethylbenzyl)phenyl]-2H-benzotriazole, reactionproduct of 2-(2-hydroxy-3-tert.butyl-5-methylpropionate)-2H-benzotriazole and polyethylene ether glycol having aweight average molecular weight of 300,2-(2-hydroxy-3-tert.butyl-5-iso-octyl propionate)-2H-benzotriazole;hydroxyphenyl s-triazines, such as,2-[4((2,-hydroxy-3-dodecyloxy/tridecyloxypropyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,2-[4(2-hydroxy-3-(2-ethylhexyl)-oxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)1,3,5-triazine,2-(4-octyloxy-2-hydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine;hydroxybenzophenone U.V. absorbers, such as, 2,4-dihydroxybenzophenone,2-hydroxy-4-octyloxybenzophenone, and2-hydroxy-4-dodecyloxybenzophenone.

Non-limiting examples of suitable hindered amine light stabilizersinclude N-(1,2,2,6,6-pentamethyl-4-piperidinyl)-2-dodecyl succinimide,N(lacetyl-2,2,6,6-tetramethyl-4-piperidinyl)-2-dodecyl succinimide,N-(2hydroxyethyl)-2,6,6,6-tetramethylpiperidine-4-ol-succinic acidcopolymer, 1,3,5 triazine-2,4,6-triamine,N,N′″-[1,2-ethanediybis[[[4,6-bis[butyl(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-1,3,5-triazine-2-yl]imino]-3,1-propanediyl]]bis[N,N′″-dibutyl-N′,N′″-bis(1,2,2,6,6-pentamethyl-4-piperidinyl)],poly-[[6-[1,1,3,3-tetramethylbutyl)-amino]-1,3,5-trianzine-2,4-diyl][2,2,6,6-tetramethylpiperidinyl)-imino]-1,6-hexane-diyl[(2,2,6,6-tetramethyl-4-piperidinyl)-imino]),bis(2,2,6,6-tetramethyl-4-piperidinyl)sebacate,bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate,bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidinyl)sebacate,bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[3,5bis(1,1-dimethylethyl-4-hydroxy-phenyl)methyl]butylpropanedioate,8-acetyl-3-dodecyl-7,7,9,9,-tetramethyl-1,3,8-triazaspiro(4,5)decane-2,4-dione,and dodecyl/tetradecyl-3-(2,2,4,4-tetramethyl-21-oxo-7-oxa-3,20-diazaldispiro(5.1.11.2)henicosan-20-yl)propionate.

Non-limiting examples of suitable antioxidants includetetrakis[methylene(3,5-di-tert-butylhydroxy hydrocinnamate)]methane,octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate,tris(2,4-di-tert-butylphenyl) phosphite,1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trioneand benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-C7-C9branched alkyl esters. In certain embodiments, the antioxidant includeshydroperoxide decomposers, such as Sanko® HCA(9,10-dihydro-9-oxa-10-phosphenanthrene-10-oxide), triphenyl phosphateand other organo-phosphorous compounds, such as, Irgafos® TNPP from CibaSpecialty Chemicals, Irgafos® 168 from Ciba Specialty Chemicals,Ultranox® 626 from GE Specialty Chemicals, Mark PEP-6 from Asahi Denka,Mark HP-10 from Asahi Denka, Irgafos® P-EPQ from Ciba SpecialtyChemicals, Ethanox 398 from Albemarle, Weston 618 from GE SpecialtyChemicals, Irgafos® 12 from Ciba Specialty Chemicals, Irgafos® 38 fromCiba Specialty Chemicals, Ultranox® 641 from GE Specialty Chemicals, andDoverphos® S-9228 from Dover Chemicals.

The coating compositions may further include other additives known inthe art for use in coating compositions. Non-limiting examples of suchadditives can include wetting agents, leveling and flow control agents,for example, Resiflow®S (polybutylacrylate), BYK® 320 and 325 (highmolecular weight polyacrylates), BYK® 347 (polyether-modified siloxane)under respective trade names, leveling agents based on (meth)acrylichomopolymers; rheological control agents; thickeners, such as partiallycrosslinked polycarboxylic acid or polyurethanes; and antifoamingagents. The other additives can be used in conventional amounts familiarto those skilled in the art. In embodiments, the wetting agents,leveling agents, flow control agents, and surfactants of the coatingcomposition can affect the surface tension of the coating compositionand thus may have an impact on the suitability of the coatingcomposition for printing. Certain wetting agents, leveling agents, flowcontrol agents, and surfactants may be incorporated into the coatingcomposition for increasing or decreasing the surface tension of thecoating composition.

Depending upon the type of crosslinking agent, the coating compositionof this invention can be formulated as one-pack (1K) or two-pack (2K)coating composition. One-pack coating compositions may be air-drycoatings or un-activated coatings. The term “air-dry coating” or“un-activated coating” refers to a coating that dries primarily bysolvent evaporation and does not require crosslinking to form a coatingfilm having desired properties. If polyisocyanates with free isocyanategroups are used as the crosslinking agent, the coating composition canbe formulated as a two-pack coating composition in that the crosslinkingagent is mixed with other components of the coating composition onlyshortly before coating application. If blocked polyisocyanates are, forexample, used as the crosslinking agent, the coating compositions can beformulated as a one-pack (1K) coating composition.

“Two-pack coating composition” or “two component coating composition”means a thermoset coating composition comprising two components storedin separate containers. These containers are typically sealed toincrease the shelf life of the components of the coating composition.The components are mixed prior to use to form a pot mix. The pot mix isapplied as a layer of desired thickness on a substrate surface, such asan automobile body or body parts. After application, the layer is curedunder ambient conditions or bake cured at elevated temperatures to forma coating on the substrate surface having desired coating properties,such as high gloss, smooth appearance, and durability.

The coating composition may have a solids content of from about 5 toabout 90, alternatively from 5 to about 80, or alternatively about 15 toabout 70, wt. %. The solids content may be determined in accordance withASTM D2369-10. In certain embodiments, the higher solids content for thecoating composition may be desired due to the coating composition notundergoing atomization utilizing conventional spray equipment.

The coating composition may include a primary or color giving pigment inan amount of from about 0.1 to about 30 weight % (wt. %), alternativelyfrom about 0.5 wt. % to about 20 wt. %, or alternatively from about 1wt. % to about 10 wt. %, based on a total weight of the coatingcomposition.

The coating composition may include the binder in an amount of fromabout 5 to about 70 wt. %, alternatively from about 10 to about 50 wt.%, or alternatively from about 15 to about 25 wt. %, based on a totalweight of the coating composition.

The coating composition may include a crosslinker in an amount of fromabout 1 to about 20 wt. %, alternatively from about 2 to about 10 wt. %,or alternatively from about 4 to about 6 wt. %, based on a total weightof the coating composition.

The coating composition may be substantially free of a dye. The term“substantially” as utilized herein means that the coating compositionmay include insignificant amounts of dye such that the color and/orproperties of the coating composition are not impacted by the additionof the insignificant amount of the dye which still being consideredsubstantially free of a dye. In embodiments, the coating compositionbeing substantially free of a dye includes no greater than 5 wt. %,alternatively no greater than 1 wt. %, or alternatively no greater than0.1 wt. %.

The system 50 may include a primer layer overlying the substrate 10, abasecoat layer overlying the primer layer, and a clearcoat layeroverlying the basecoat layer. It is to be appreciated that the system 50can include an additional layer or layers, such as any of the coatinglayers described above, with the additional layers disposed in anyposition between, above, or below the primer layer, the basecoat layer,and/or the clearcoat layer. In embodiments, the coating composition maybe utilized to form the primer layer, the basecoat layer, the clearcoatlayer, or combinations thereof. In certain embodiments, the coatingcomposition is utilized to form the basecoat layer.

A process for coating a substrate 10 utilizing the coating compositionis also provided herein. The process includes the step of applying afirst coating composition, including the coating composition describedabove, over at least a portion of the substrate 10 to form a first wetcoating layer. The process may further include the step of curing ordrying the first wet coating layer at a temperature in a range of fromabout 18° C. (64° F.) to about 180° C. (356° F.) to form a first drycoating layer over the substrate 10. The first wet coating layer may becured or dried for an amount of time from about 10 minutes to about 3days. The process may further include the step of allowing the first wetcoating layer to flash. The process may further include the stepapplying a second coating composition to the substrate 10 to form amulti-layer coating. In certain embodiments, the second coatingcomposition may be applied over the first wet coating layer to form asecond wet coating layer and curing the first and the second wet coatinglayers together to form the multi-layer coating, wherein the secondcoating composition is the same or different from the first coatingcomposition. In other embodiments, the second coating composition isapplied over the first dry coating layer to form a second wet coatinglayer and curing the second wet coating layer to form the multi-layercoating, wherein the second coating composition is the same or differentfrom the first coating composition. In various embodiments, the firstcoating composition is a basecoat composition and the second coatingcomposition is a clearcoat composition. In other embodiments, both thefirst coating composition and the second coating composition arebasecoat compositions.

A method of applying a coating composition to the substrate 10 utilizingthe high transfer efficiency applicator 12 including a nozzle isprovided herein. The nozzle defines a nozzle orifice having a nozzlediameter of from 0.00002 m to 0.0004 m. The coating composition includesthe carrier and the binder. The coating composition may have a viscosityof from about 0.002 Pa*s to about 0.2 Pa*s, a density of from about 838kg/m³ to about 1557 kg/m³, a surface tension of from about 0.015 N/m toabout 0.05 N/m, and a relaxation time of from about 0.0005 s to about0.02 s. The method includes the step of providing the coatingcomposition to the high transfer efficiency applicator 12. The methodfurther includes the step of applying the coating composition to thesubstrate 10 through the nozzle orifice 72 to form the coating layer. Itis to be appreciated that ranges for the nozzle diameter, viscosity,density, surface tension, and relaxation time may be defined by any ofthe ranges described herein.

A method of applying a coating composition to the substrate 10 utilizingthe high transfer efficiency applicator 12 including a nozzle isprovided herein. The nozzle defines a nozzle orifice having a nozzlediameter of from 0.00002 m to 0.0004 m. The coating composition includesthe carrier and the binder. The coating composition may have anOhnesorge number (Oh) of from about 0.01 to about 12.6, the coatingcomposition may have a Reynolds number (Re) of from about 0.02 to about6,200, and the coating composition may have a Deborah number (De) offrom greater than 0 to about 1730, The method includes the step ofproviding the coating composition to the high transfer efficiencyapplicator 12. The method further includes the step of applying thecoating composition to the substrate 10 through the nozzle orifice 72 toform the coating layer.

A method of applying a first coating composition and a second coatingcomposition utilizing a first high transfer efficiency applicator 88 anda second high transfer efficiency applicator 90 is also provided herein.The first high transfer efficiency applicator 88 includes a first nozzleand the first nozzle defines a first nozzle orifice 92. The second hightransfer efficiency applicator 90 includes a second nozzle and thesecond nozzle defines a second nozzle orifice 94. The method includesthe step of providing a substrate 10 defining a first target area 80 anda second target area 82. The method further includes the step ofapplying the first coating composition through the first nozzle orifice92 to first target area 80 of the substrate 10. The method furtherincludes the step of applying the second coating composition through thesecond nozzle orifice 94 to second target area 82 of the substrate 10.

The first high transfer efficiency applicator 88 includes a plurality ofthe first nozzles with each of the first nozzles defining the firstnozzle orifice 92. The second high transfer efficiency applicator 90includes a plurality of the second nozzles with each of the secondnozzles defining the second nozzle orifice 94. The step of applying thefirst coating composition is further defined as expelling the firstcoating composition through each of the first nozzle orifice 92 sindependent of one another. The step of applying the second coatingcomposition is further defined as expelling the second coatingcomposition through each of the second nozzle orifice 94 s independentof one another.

The substrate 10 includes a first end and a second end with the firsttarget area 80 of the substrate 10 and the second target area 82 of thesubstrate 10 disposed therebetween. The method further includes the stepof moving the first high transfer efficiency applicator 88 and thesecond high transfer efficiency applicator 90 from the first end to thesecond end. The steps of expelling the first coating composition and thesecond coating composition through the first nozzle orifice 92 and thesecond nozzle orifice 94 are performed along a single pass from thefirst end to the second end.

A method of applying a coating composition utilizing a first hightransfer efficiency applicator 88 and a second high transfer efficiencyapplicator 90. The first high transfer efficiency applicator 88 includesa first nozzle. The first nozzle defines a first nozzle orifice 92. Thesecond high transfer efficiency applicator 90 includes a second nozzle.The second nozzle defines a second nozzle orifice 94. The methodincludes the step of providing a substrate 10 defining a first targetarea 80 and a second target area 82. The method includes the step ofapplying the coating composition through the first nozzle orifice 92 tofirst target area 80 of the substrate 10. The method includes the stepof applying the coating composition through the second nozzle orifice 94to second target area 82 of the substrate 10.

The first high transfer efficiency applicator 88 includes a plurality ofthe first nozzles with each of the first nozzles defining the firstnozzle orifice 92. The second high transfer efficiency applicator 90includes a plurality of the second nozzles with each of the secondnozzles defining the second nozzle orifice 94. The step of applying thecoating composition is further defined as expelling the coatingcomposition through each of the first nozzle orifice 92 s independent ofone another. The step of applying the coating composition is furtherdefined as expelling the coating composition through each of the secondnozzle orifice 94 s independent of one another.

The substrate 10 includes a first end and a second end with the firsttarget area 80 of the substrate 10 and the second target area 82 of thesubstrate 10 disposed therebetween. The method further includes the stepof moving the first high transfer efficiency applicator 88 and thesecond high transfer efficiency applicator 90 from the first end to thesecond end. The steps of expelling the coating composition through thefirst nozzle orifice 92 and the second nozzle orifice 94 are performedalong a single pass from the first end to the second end.

Another system for applying the coating composition by the high transferefficiency applicator 12 is also provided herein. The system may exhibitimproved efficiency, reduced environmental impact, and reduced cost dueto reduced waste. The system may include a reduced number of airhandlers due to the elimination of overspray and atomization by lowtransfer efficiency application methods. The system may exhibit areduction or elimination of waste treatment due to the elimination ofoverspray and atomization by low transfer efficiency applicationmethods. The system may exhibit a reduction or elimination of maskingand demasking of the substrate 10 due to the ability of the hightransfer efficiency applicator 12 to directly apply droplets 74 of thecoating composition to the substrate 10. The system may exhibit areduction or elimination of clean-up and maintenance of environmentalsystems or booth surfaces due to the elimination of overspray andatomization by low transfer efficiency application methods. The systemmay exhibit a reduction or elimination of baking processes by utilizingUV/EB/laser excitable coatings with the high transfer efficiencyapplicator 12 and an appropriate energy source.

Another system for applying a coating composition to a substrate 10utilizing a high transfer efficiency applicator is provided herein. Thesystem includes a high transfer efficiency applicator including anozzle. The nozzle defines a nozzle orifice having a nozzle diameter inan amount of from about 0.00002 m to about 0.0004 m. The system furtherincludes a reservoir in fluid communication with the high transferefficiency applicator and configured to contain the coating composition.The high transfer efficiency applicator is configured to receive thecoating composition from the reservoir and configured to expel thecoating composition through the nozzle orifice 72 to the substrate 10 toform a coating layer. At least 80% of the droplets of the coatingcomposition expelled from the high transfer efficiency applicatorcontact the substrate 10.

In certain embodiments, the substrate 10 is disposed within anenvironment including an overspray capture device 102. An air flow maymove through the environment and to the overspray capture device 102. Nomore than 20 wt. % of the coating composition expelled from the hightransfer efficiency applicator may contact the overspray capture device102, based on a total weight of the coating composition. In otherembodiments, no more than 15 wt. %, alternatively no more than 10 wt. %,alternatively no more than 5 wt. %, alternatively no more than 3 wt. %,alternatively no more than 2 wt. %, or alternatively no more than 0.1wt. %, of the coating composition expelled from the high transferefficiency applicator may contact the overspray capture device 102,based on a total weight of the coating composition. The overspraycapture device 102 may include a filter, a scrubber, or combinationsthereof.

Additional considerations may include, but are not limited to:

Multipass printing is preferred. strictly one pass will result in avisible defect. While one might consider multipass to be an inherentlyslower printing process, one could think about a pseudo-multipassprocess using 2 or more staggered printheads printed in a single passmanner. Such a process (as well as true multipass) could offer thelatitude of increasing the film build by depositing more paint or,alternatively, jetting smaller droplets which may have other advantages.Printing on vertical surfaces. Because of the low viscosity requirementsfor jetting, the usual approach for enabling printing on verticalsurfaces of imparting shear thinning to coating formulation may not bepossible. Alternative approaches that could be considered include:A. Two printhead jetting: in addition to a high transfer efficiencyapplicator to deposit paint onto substrate 10, a second high transferefficiency applicator is used to deposit an “activator” of some sorts.This activator when contacting/mixing with the paint on substrate 10will cause the paint to thicken thereby inhibiting sagging/slumping.Examples of such activators might be to induce a pH or solvency change.B. Temperature change: paint in the high transfer efficiency applicatoris at an elevated temperature, but after jetting, temperature is reduceddue to both ambient conditions as well as solvent evaporation prior todeposition on substrate 10.

In other embodiments, an electronic imaging device may be utilized togenerate a target image data of a target coating to be applied to thesubstrate utilizing the high transfer efficiency applicator. The targetimage data may relate to color, brightness, hue, chroma, or otherappearance features. A color matching protocol may be utilized toanalyze the target image data pixel by pixel to generate applicationinstructions. In certain embodiments, a mathematical model can beutilized to determine values of the target image data based on thepixels within an image to generate target image values. The resultingone or more target image values may be compared to a sample databasethat has produced similar sample image values based on sample coatings,where the sample coatings are prepared and analyzed to provide a samplecoating formula that provides a specific appearance.

A system for applying a coating composition to a substrate utilizing ahigh transfer efficiency applicator is provide herein. The systemincludes a storage device for storing instructions for performing amatching protocol. The system further includes one or more dataprocessors configured to execute the instructions to: receive, by one ormore data processors, target image data of a target coating, the targetimage data generated by an electronic imaging device; and apply thetarget image data to a matching protocol to generate applicationinstructions.

The system further includes a high transfer efficiency applicatorincluding a nozzle and the nozzle defines a nozzle orifice having anozzle diameter of from about 0.00002 m to about 0.0004 m. The systemfurther includes a reservoir in fluid communication with the hightransfer efficiency applicator and configured to contain the coatingcomposition. The high transfer efficiency applicator is configured toreceive the coating composition from the reservoir and configured toexpel the coating composition through the nozzle orifice 72 to thesubstrate to form a coating layer. The high transfer efficiencyapplicator is configured expel the coating composition based on theapplication instructions.

EXAMPLES

Examples 1-5 below describe the preparation of various coatingcompositions of this disclosure.

Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Component Layered silicate 0.01 — 0.010.01 0.01 rheology control agent Alkali swellable 0.14 — 0.14 0.14 0.14emulsion thickening agent Polyester-Polyurethane 6.0 6.0 6.0 6.0 6.0Dispersion I Styrene-acrylic 4.3 4.3 4.3 4.3 4.3 latex dispersionPolyester-Polyurethane 3.5 3.5 — 3.5 3.5 Dispersion IIPolyester-Polyurethane — — 3.5 — — Dispersion III Melamine-formaldehyde2.5 2.5 2.5 2.5 2.5 resin Dispersion of 1.2 1.2 1.2 — — micronized talcextender pigment Dispersion of — — — 1.2 2.4 micronized barium sulfateextender pigment Dispersion of 0.9 0.9 0.9 0.9 0.9 amorphous carbonblack pigment Dispersion of 0.1 0.1 0.1 0.1 0.1 indanthrone blue 60pigment Solution of 1,2 0.29  0.29 0.29 0.29 0.29 chrome complex blackdye Properties Viscosity (mPa s) 120 10   133 146 146 (250 1/s) pH 8.98.9 8.8 9.0 8.9 Solids Content (wt. %) 20.3 — 21.0 21.2 22.2Layered silicate rheology control agent is provided in a solution ofwater and polypropylene glycol which is similar to a solutioncommercially available from Altana under the trade name Laponite RD.Alkali swellable emulsion thickening agent is provided as solution in10% water which is similar to a solution commercially available fromBASF under the trade name Rheovis AS1130.Polyester-Polyurethane Dispersion I is a polyester-polyurethane polymerhaving the tradename Bayhydrol® U 241 which is commercially availablefrom Covestro AG of Leverkusen, Germany.Styrene-acrylic latex dispersion is formed by a two-step emulsionpolymerization process.Polyester-Polyurethane Dispersion II is a polyurethane dispersion resinformed from a linear polyester diol resin (reaction product of monomers1,6-hexanediol, adipic acid, andisophthalic acid) and isophorone diisocyanate. Thispolyester-polyurethane polymer has a weight average molecular weight ofabout 30,000, a solids content of about 35 wt. %, and a particle size ofabout 250 nanometers.Polyester-Polyurethane Dispersion III is a polyurethane dispersion resinformed from a linear polycarbonate-polyester and isophoronediisocyanate. This polyester-polyurethane polymer has a weight averagemolecular weight of about 75,000, a solids content of about 35 wt. %,and a particle size of about 180 nanometers.Melamine-formaldehyde resin is similar to a hexa(methoxymethyl)melamine(HMMM) commercially available from Allnex under the trade name Cymel303.Dispersion of micronized talc extender pigment is similar to an extenderpigment commercially available from Imerys under the trade name MistronMonomix.Dispersion of micronized barium sulfate extender pigment is similar toan extender pigment commercially available from Huntsman under the tradename Blanc Fixe F.Dispersion of amorphous carbon black pigment is similar to a carbonblack pigment commercially available from Birla Carbon under the tradename Raven 5000 Ultra II.Dispersion of indanthrone blue 60 pigment is similar to an extenderpigment commercially available from Heucotech under the trade nameMonolite Blue 3RX H.Solution of 1,2 chrome complex black dye is similar to an extenderpigment commercially available from BASF under the trade name OrasolBlack X55.

With reference to FIG. 20 , each of the exemplary coating compositionsexhibits a difference in elasticity and shear viscosity based on thecomponents of the exemplary coating compositions.

Examples 6-10 below describe the preparation of various coatingcompositions of this disclosure. A conventional black monocoat with 11to 75 weight percent reduction with butyl acetate was evaluated which iscompositionally similar to a black monocoat commercially available fromAxalta Coating Systems under the tradename ChromaDyne™ The examples havethe following properties.

Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Component Conventional black 100 100 100100 100 monocoat Butyl acetate 11 20 45 75 45 Cellulose Acetate — — — —0.01 Butyrate Properties Viscosity at 1000 49.7 31.1 11.8 5.4 12.1 sec 1(mPa · s) Surface tension 27.5 26.8 26.7 26.5 27.2 (mN/m)Conventional black monocoat is similar to a black monocoat commerciallyavailable from Axalta Coating Systems under the tradename ChromaDyne™

Cellulose Acetate Butyrate is commercially available from EastmanChemical Company under the trade name CAB 381-20. While at least oneexemplary embodiment has been presented in the foregoing detaileddescription, it should be appreciated that a vast number of variationsexist. It should also be appreciated that the exemplary embodiment orexemplary embodiments are only examples, and are not intended to limitthe scope, applicability, or configuration in any way. Rather, theforegoing detailed description will provide those skilled in the artwith a convenient road map for implementing an exemplary embodiment. Itbeing understood that various changes may be made in the function andarrangement of elements described in an exemplary embodiment withoutdeparting from the scope as set forth in the appended claims.

What is claimed is:
 1. A method of applying a coating composition to asubstrate utilizing a high transfer efficiency applicator, said methodcomprising the steps of: providing the high transfer efficiencyapplicator comprising an array of nozzles wherein each nozzle defines anozzle orifice having a diameter of from 0.00002 m to 0.0004 m;providing the coating composition; and applying the coating compositionto the substrate through the nozzle orifice without atomization suchthat at least 99.9% of the applied coating composition contacts thesubstrate to form a coating layer having a wet thickness of at least 5microns; wherein the coating composition comprises: a carrier; a binderpresent in an amount of from 5 to about 70 weight percent based on atotal weight of the coating composition; a crosslinker present in anamount of from about 0.1 to about 25 weight percent based on a totalweight of the coating composition; and a radar reflective pigment or aLiDAR reflective pigment; and wherein the coating composition has (1) asolids content of from about 5 to about 70 weight % based on a totalweight of the coating composition as measured in accordance with ASTMD2369; (2) a viscosity of from about 0.002 Pa*s to about 0.2 Pa*s asmeasured according to ASTM 7867-13 with cone-and-plate or parallelplates at a shear rate of 1000 sec−1; (3) a density of from about 838kg/m³ to about 1557 kg/m³; (4) a surface tension of from about 0.015 N/mto about 0.05 N/m; (5) a relaxation time of from about 0.00001 to about1 s; (6) an Ohnesorge number (Oh) of from about 0.01 to about 12.6 thatis determined in accordance with equation I, as follows:Oh=(η/√{square root over (ρσD)})  (I), wherein η represents viscosity ofthe coating composition in pascal-seconds (Pa*s), ρ represents densityof the coating composition in kilograms per cubic meter (kg/m³), σrepresents surface tension of the coating composition in newtons permeter (N/m), and D represents nozzle diameter of the high transferefficiency applicator in meters (m); (7) a Reynolds number (Re) of fromabout 0.02 to about 6,200 that is determined in accordance with equationII, as follows:Re=(ρvD/η)  (II), wherein ρ represents density of the coatingcomposition in kilograms per cubic meter (kg/m³), v represents impactvelocity of the high transfer efficiency applicator in meters per second(m/s), D represents nozzle diameter of the high transfer efficiencyapplicator in meters (m), and η represents viscosity of the coatingcomposition in pascal-seconds (Pa*s); and (8) a Deborah number (De) offrom greater than 0 to about 1730 that is determined in accordance withequation III, as follows:De=λ/√{square root over (ρD ³/σ)}  (III), wherein λ representsrelaxation time of the coating composition in seconds (s), ρ representsdensity of the coating composition in kilograms per cubic meter (kg/m³),D represents nozzle diameter of the high transfer efficiency applicatorin meters (m), and σ represents surface tension of the coatingcomposition in newtons per meter (N/m); and wherein the impact velocityis from about 0.2 m/s to about 20 m/s.
 2. The method of claim 1, whereinthe Ohnesorge number (Oh) is from 0.01 to 12.6 and is further definedbased upon the following equations V and VI, in view of the Reynoldsnumber (Re),Oh is no greater than 10{circumflex over( )}(−0.5006*log(Re)+1.2135)  (V), andOh is at least 10{circumflex over ( )}(−0.5435*log(Re)−1.0324)  (VI),wherein the Reynolds number (Re) is from 0.02 to 6,200.
 3. The method ofclaim 1, wherein the coating composition has an Ohnesorge number (Oh) offrom about 0.05 to about 1.8, a Reynolds number (Re) of from about 0.3to about 660, and a Deborah number (De) of from greater than 0 to about46.
 4. The method of claim 3, wherein the Ohnesorge number (Oh) isfurther defined based upon the following equations VII and VIII, in viewof the Reynolds number (Re),Oh is no greater than 10{circumflex over( )}(−0.5067*log(Re)+0.706)  (VII), andOh is at least 10{circumflex over ( )}(−0.5724*log(Re)−0.4876)  (VIII),wherein the Reynolds number (Re) is from 0.3 to
 660. 5. The method ofclaim 1, wherein the coating composition comprises the LiDAR reflectivepigment in an amount of from about 0.1 to about 5 wt % based on a totalweight of the coating composition.
 6. The method of claim 2, wherein thecoating composition comprises the LiDAR reflective pigment in an amountof from about 0.1 to about 5 wt % based on a total weight of the coatingcomposition.
 7. The method of claim 3, wherein the coating compositioncomprises the LiDAR reflective pigment in an amount of from about 0.1 toabout 5 wt % based on a total weight of the coating composition.
 8. Themethod of claim 4, wherein the coating composition comprises the LiDARreflective pigment in an amount of from about 0.1 to about 5 wt % basedon a total weight of the coating composition.
 9. The method of claim 1,wherein the coating composition is substantially free of a dye.
 10. Themethod of claim 1, wherein the coating composition further comprises asolvent selected from the group of water, a non-aqueous solvent, and acombination thereof.
 11. The method of claim 1, wherein the coatingcomposition has a viscosity of from about 0.005 Pa*s to about 0.05 Pa*sas measured according to ASTM 7867-13 with cone-and-plate or parallelplates at a shear rate of 1000 sec−1, a density of from about 958 kg/m³to about 1319 kg/m³, and a surface tension of from about 0.02 N/m toabout 0.032 N/m.
 12. The method of claim 2, wherein the coatingcomposition has a viscosity of from about 0.005 Pa*s to about 0.05 Pa*sas measured according to ASTM 7867-13 with cone-and-plate or parallelplates at a shear rate of 1000 sec−1, a density of from about 958 kg/m³to about 1319 kg/m³, and a surface tension of from about 0.02 N/m toabout 0.032 N/m.
 13. The method of claim 3, wherein the coatingcomposition has a viscosity of from about 0.005 Pa*s to about 0.05 Pa*sas measured according to ASTM 7867-13 with cone-and-plate or parallelplates at a shear rate of 1000 sec−1, a density of from about 958 kg/m³to about 1319 kg/m³, and a surface tension of from about 0.02 N/m toabout 0.032 N/m.
 14. The method of claim 4, wherein the coatingcomposition has a viscosity of from about 0.005 Pa*s to about 0.05 Pa*sas measured according to ASTM 7867-13 with cone-and-plate or parallelplates at a shear rate of 1000 sec−1, a density of from about 958 kg/m³to about 1319 kg/m³, and a surface tension of from about 0.02 N/m toabout 0.032 N/m.
 15. The method of claim 5, wherein the coatingcomposition has a viscosity of from about 0.005 Pa*s to about 0.05 Pa*sas measured according to ASTM 7867-13 with cone-and-plate or parallelplates at a shear rate of 1000 sec−1, a density of from about 958 kg/m³to about 1319 kg/m³, and a surface tension of from about 0.02 N/m toabout 0.032 N/m.
 16. The method of claim 1 wherein the coatingcomposition has an Ohnesorge number (Oh) of from about 0.05 to about1.8, a Reynolds number (Re) of from about 0.3 to about 660, and aDeborah number (De) of from greater than 0 to about 46; the coatingcomposition comprises the LiDAR reflective pigment in an amount of fromabout 0.1 to about 5 wt % based on a total weight of the coatingcomposition; the coating composition is substantially free of a dye; thecoating composition further comprises a solvent selected from the groupof water, a non-aqueous solvent, and a combination thereof; and thecoating composition has a viscosity of from about 0.005 Pa*s to about0.05 Pa*s as measured according to ASTM 7867-13 with cone-and-plate orparallel plates at a shear rate of 1000 sec−1, a density of from about958 kg/m³ to about 1319 kg/m³, and a surface tension of from about 0.02N/m to about 0.032 N/m.